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	<id>https://michaelnielsen.org/polymath/index.php?action=history&amp;feed=atom&amp;title=W-trick</id>
	<title>W-trick - Revision history</title>
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	<updated>2026-04-04T13:29:13Z</updated>
	<subtitle>Revision history for this page on the wiki</subtitle>
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	<entry>
		<id>https://michaelnielsen.org/polymath/index.php?title=W-trick&amp;diff=8368&amp;oldid=prev</id>
		<title>WikiSysop: Reverted edits by Cheaptara (Talk) to last version by Teorth</title>
		<link rel="alternate" type="text/html" href="https://michaelnielsen.org/polymath/index.php?title=W-trick&amp;diff=8368&amp;oldid=prev"/>
		<updated>2013-07-05T10:05:41Z</updated>

		<summary type="html">&lt;p&gt;Reverted edits by &lt;a href=&quot;/polymath/index.php?title=Special:Contributions/Cheaptara&quot; title=&quot;Special:Contributions/Cheaptara&quot;&gt;Cheaptara&lt;/a&gt; (&lt;a href=&quot;/polymath/index.php?title=User_talk:Cheaptara&amp;amp;action=edit&amp;amp;redlink=1&quot; class=&quot;new&quot; title=&quot;User talk:Cheaptara (page does not exist)&quot;&gt;Talk&lt;/a&gt;) to last version by &lt;a href=&quot;/polymath/index.php?title=User:Teorth&quot; title=&quot;User:Teorth&quot;&gt;Teorth&lt;/a&gt;&lt;/p&gt;
&lt;table style=&quot;background-color: #fff; color: #202122;&quot; data-mw=&quot;interface&quot;&gt;
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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 03:05, 5 July 2013&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l1&quot;&gt;Line 1:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 1:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;  &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Be certain which you get only these screen sets &lt;/del&gt;that &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;may viewable from any angle&lt;/del&gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;The W-trick is a simple trick to remove some of the structure from the set of primes, and also to increase the density of primes slightly.  Basically, instead of looking at the set &amp;lt;math&amp;gt;{\mathcal P} := \{2,3,5,7,\ldots\}&amp;lt;/math&amp;gt; of primes, one instead looks at the set &amp;lt;math&amp;gt;{\mathcal P}_{W,b} := \{ n: Wn+b \in {\mathcal P} \}&amp;lt;/math&amp;gt;, where &amp;lt;math&amp;gt;W := \prod_{p \leq w} p&amp;lt;/math&amp;gt; is the product of all primes less than some threshold w, and b is a number coprime to W (in many cases one can just take b=1). &lt;/ins&gt; &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;It is a result in elementary number theory &lt;/ins&gt;that &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&amp;lt;math&amp;gt;W = \exp((1+o(1))w)&amp;lt;/math&amp;gt;, thus W is of exponential size in w.  If one seeks primes less than N, one must therefore set w no larger than &amp;lt;math&amp;gt;\log N&amp;lt;/math&amp;gt; or so&lt;/ins&gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt; [http:&lt;/del&gt;//&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;www.dvdmoviessaleuk.co.uk&lt;/del&gt;/ &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Buy dvd] &lt;/del&gt;, &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Find more information &lt;/del&gt;about &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Mac DVD &lt;/del&gt;to &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Audio Converter suggestions from Top Mac Application Online Shop.&lt;/del&gt;which &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;includes simpsons&lt;/del&gt;,&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;south park,Walt Disney&#039;s 100 Years Of Magic,Family Guy Seasons and so on,A portion &lt;/del&gt;of the &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;goods is no cost shipping, purchase inexpensive dvds, A variety of of discounts attainable at dvdexcellent,welcome &lt;/del&gt;to &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;our on line store&lt;/del&gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;The set &amp;lt;math&amp;gt;{\mathcal P}_{W,b}&amp;lt;&lt;/ins&gt;/&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;math&amp;gt; is a little bit denser than the primes; the primes less than N have density about &amp;lt;math&amp;gt;1&lt;/ins&gt;/&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;\log N&amp;lt;&lt;/ins&gt;/&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;math&amp;gt; by the prime number theorem, but &amp;lt;math&amp;gt;{\mathcal P}_{W&lt;/ins&gt;,&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;b}&amp;lt;/math&amp;gt; has density &lt;/ins&gt;about &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&amp;lt;math&amp;gt; \frac{W}{\phi(W)} \frac{1}{\log N} \approx \frac{\log w}{\log N}&amp;lt;/math&amp;gt;; raising w &lt;/ins&gt;to &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&amp;lt;math&amp;gt;O(\log N)&amp;lt;/math&amp;gt; (&lt;/ins&gt;which &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;is the largest feasible value)&lt;/ins&gt;, &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;the density &lt;/ins&gt;of the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;W-tricked primes thus increases slightly from &amp;lt;math&amp;gt;1/\log N&amp;lt;/math&amp;gt; &lt;/ins&gt;to &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;about &amp;lt;math&amp;gt;\log \log N / \log N&amp;lt;/math&amp;gt;&lt;/ins&gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt; [http://www.shopdvdmoviesonline.com/ Buy dvd] &lt;/del&gt;,&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Practically nothing beats a rest day with household, mates or acquaintances.&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;The W-tricked primes &amp;lt;math&amp;gt;{\mathcal P}_{W&lt;/ins&gt;,&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;b}&amp;lt;&lt;/ins&gt;/&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;math&amp;gt; also behave more &#039;pseudorandomly&lt;/ins&gt;&#039; &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;than &lt;/ins&gt;the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;primes themselves&lt;/ins&gt;.  &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;For instance&lt;/ins&gt;, the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;primes &lt;/ins&gt;are &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;of course highly biased to favour odd numbers over even numbers&lt;/ins&gt;, &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;but &lt;/ins&gt;the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;W-tricked primes have no such bias once w &lt;/ins&gt;is &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;at least 2 (by &lt;/ins&gt;the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;prime number theorem in arithmetic progressions).  More generally&lt;/ins&gt;, the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;primes do not equidistribute modulo q for any q&lt;/ins&gt;, &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;but the W-tricked primes do &lt;/ins&gt;as &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;soon &lt;/ins&gt;as &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;w &lt;/ins&gt;is &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;greater than or equal to &lt;/ins&gt;all the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;prime factors of q&lt;/ins&gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-added&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt; [http:&lt;/del&gt;/&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;/www.populardvdonline.com/ Dvd] , Although headrest car DVD player isn&lt;/del&gt;&#039;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;t the coolest and most entertaining way for you to pimp your car or truck but to make your time within &lt;/del&gt;the &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;road much more enjoyable&lt;/del&gt;.&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-added&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-added&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;  &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;[http://www.dvdshopaustralia.com/ Buy dvd] &lt;/del&gt;, &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Incorporated in &lt;/del&gt;the &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;package &lt;/del&gt;are &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;AC/DC adaptor&lt;/del&gt;, &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;AV cable, auto charger and headrests mounting Velcro strap. Installing this necessary leisure device will make your travel relaxing. Shops frequently give a restricted alternative as well as expense are often a little bit increased when compared with what companies give. Among &lt;/del&gt;the &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;reasons for that &lt;/del&gt;is &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;definitely that despite &lt;/del&gt;the &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;fact that they change their all round design consistently&lt;/del&gt;, the &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;color&lt;/del&gt;, &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;background &lt;/del&gt;as &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;well &lt;/del&gt;as &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;the dimensions of the symbol always remain exactly the same. For years, he had brought the benefits of the most recent technologies inside the DVD marketplace.&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-added&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-added&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt; [http://www.dvdfortvshowes.com/ Blu ray dvds] , Getting this kind of accessory &lt;/del&gt;is &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;really a assure for any additional comfortable trip. We promise that &lt;/del&gt;all the &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;postage might be charged by your actual product&#039;s weight, there won&#039;t be any future extra charge: insurance&amp;amp;tax&lt;/del&gt;.&lt;/div&gt;&lt;/td&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-added&quot;&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>WikiSysop</name></author>
	</entry>
	<entry>
		<id>https://michaelnielsen.org/polymath/index.php?title=W-trick&amp;diff=8365&amp;oldid=prev</id>
		<title>Cheaptara at 05:30, 5 July 2013</title>
		<link rel="alternate" type="text/html" href="https://michaelnielsen.org/polymath/index.php?title=W-trick&amp;diff=8365&amp;oldid=prev"/>
		<updated>2013-07-05T05:30:07Z</updated>

		<summary type="html">&lt;p&gt;&lt;/p&gt;
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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 22:30, 4 July 2013&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l1&quot;&gt;Line 1:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 1:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;The W-trick is a simple trick to remove some of the structure from the set of primes, and also to increase the density of primes slightly.  Basically, instead of looking at the set &amp;lt;math&amp;gt;{\mathcal P} := \{2,3,5,7,\ldots\}&amp;lt;/math&amp;gt; of primes, one instead looks at the set &amp;lt;math&amp;gt;{\mathcal P}_{W,b} := \{ n: Wn+b \in {\mathcal P} \}&amp;lt;/math&amp;gt;, where &amp;lt;math&amp;gt;W := \prod_{p \leq w} p&amp;lt;/math&amp;gt; is the product of all primes less than some threshold w, and b is a number coprime to W (in many cases one can just take b=1). &lt;/del&gt; &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;It is a result in elementary number theory &lt;/del&gt;that &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&amp;lt;math&amp;gt;W = \exp((1+o(1))w)&amp;lt;/math&amp;gt;, thus W is of exponential size in w.  If one seeks primes less than N, one must therefore set w no larger than &amp;lt;math&amp;gt;\log N&amp;lt;/math&amp;gt; or so&lt;/del&gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;  &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Be certain which you get only these screen sets &lt;/ins&gt;that &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;may viewable from any angle&lt;/ins&gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;The set &amp;lt;math&amp;gt;{\mathcal P}_{W,b}&amp;lt;&lt;/del&gt;/&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;math&amp;gt; is a little bit denser than the primes; the primes less than N have density about &amp;lt;math&amp;gt;1&lt;/del&gt;/&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;\log N&amp;lt;&lt;/del&gt;/&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;math&amp;gt; by the prime number theorem, but &amp;lt;math&amp;gt;{\mathcal P}_{W&lt;/del&gt;,&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;b}&amp;lt;/math&amp;gt; has density &lt;/del&gt;about &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&amp;lt;math&amp;gt; \frac{W}{\phi(W)} \frac{1}{\log N} \approx \frac{\log w}{\log N}&amp;lt;/math&amp;gt;; raising w &lt;/del&gt;to &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&amp;lt;math&amp;gt;O(\log N)&amp;lt;/math&amp;gt; (&lt;/del&gt;which is &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;the largest feasible value)&lt;/del&gt;, &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;the density &lt;/del&gt;of &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;the W-tricked primes thus increases slightly from &amp;lt;math&amp;gt;1/\log N&amp;lt;/math&amp;gt; &lt;/del&gt;to &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;about &amp;lt;math&amp;gt;\log \log N / \log N&amp;lt;/math&amp;gt;&lt;/del&gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt; [http:&lt;/ins&gt;//&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;www.dvdmoviessaleuk.co.uk&lt;/ins&gt;/ &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Buy dvd] &lt;/ins&gt;, &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Find more information &lt;/ins&gt;about &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Mac DVD &lt;/ins&gt;to &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Audio Converter suggestions from Top Mac Application Online Shop.&lt;/ins&gt;which &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;includes simpsons,south park,Walt Disney&#039;s 100 Years Of Magic,Family Guy Seasons and so on,A portion of the goods &lt;/ins&gt;is &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;no cost shipping, purchase inexpensive dvds&lt;/ins&gt;, &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;A variety of &lt;/ins&gt;of &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;discounts attainable at dvdexcellent,welcome &lt;/ins&gt;to &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;our on line store&lt;/ins&gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;The W-tricked primes &amp;lt;math&amp;gt;{\mathcal P}_{W&lt;/del&gt;,&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;b}&amp;lt;&lt;/del&gt;/&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;math&amp;gt; also behave more &lt;/del&gt;&#039;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;pseudorandomly&#039; than &lt;/del&gt;the &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;primes themselves&lt;/del&gt;.  &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;For instance&lt;/del&gt;, the &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;primes &lt;/del&gt;are &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;of course highly biased to favour odd numbers over even numbers&lt;/del&gt;, &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;but &lt;/del&gt;the &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;W-tricked primes have no such bias once w &lt;/del&gt;is &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;at least 2 (by &lt;/del&gt;the &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;prime number theorem in arithmetic progressions).  More generally&lt;/del&gt;, the &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;primes do not equidistribute modulo q for any q&lt;/del&gt;, &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;but the W-tricked primes do &lt;/del&gt;as &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;soon &lt;/del&gt;as &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;w &lt;/del&gt;is &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;greater than or equal to &lt;/del&gt;all the &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;prime factors of q&lt;/del&gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt; [http://www.shopdvdmoviesonline.com/ Buy dvd] &lt;/ins&gt;,&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Practically nothing beats a rest day with household, mates or acquaintances.&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
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&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;  &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;[http://www.dvdshopaustralia.com/ Buy dvd] &lt;/ins&gt;, &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Incorporated in &lt;/ins&gt;the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;package &lt;/ins&gt;are &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;AC/DC adaptor, AV cable&lt;/ins&gt;, &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;auto charger and headrests mounting Velcro strap. Installing this necessary leisure device will make your travel relaxing. Shops frequently give a restricted alternative as well as expense are often a little bit increased when compared with what companies give. Among &lt;/ins&gt;the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;reasons for that &lt;/ins&gt;is &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;definitely that despite &lt;/ins&gt;the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;fact that they change their all round design consistently&lt;/ins&gt;, the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;color&lt;/ins&gt;, &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;background &lt;/ins&gt;as &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;well &lt;/ins&gt;as &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;the dimensions of the symbol always remain exactly the same. For years, he had brought the benefits of the most recent technologies inside the DVD marketplace.&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt; [http://www.dvdfortvshowes.com/ Blu ray dvds] , Getting this kind of accessory &lt;/ins&gt;is &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;really a assure for any additional comfortable trip. We promise that &lt;/ins&gt;all the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;postage might be charged by your actual product&#039;s weight, there won&#039;t be any future extra charge: insurance&amp;amp;tax&lt;/ins&gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Cheaptara</name></author>
	</entry>
	<entry>
		<id>https://michaelnielsen.org/polymath/index.php?title=W-trick&amp;diff=2199&amp;oldid=prev</id>
		<title>Teorth at 18:11, 3 August 2009</title>
		<link rel="alternate" type="text/html" href="https://michaelnielsen.org/polymath/index.php?title=W-trick&amp;diff=2199&amp;oldid=prev"/>
		<updated>2009-08-03T18:11:29Z</updated>

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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 11:11, 3 August 2009&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l1&quot;&gt;Line 1:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 1:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The W-trick is a simple trick to remove some of the structure from the set of primes, and also to increase the density of primes slightly.  Basically, instead of looking at the set &amp;lt;math&amp;gt;{\mathcal P} := \{2,3,5,7,\ldots\}&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;$ &lt;/del&gt;of primes, one instead looks at the set &amp;lt;math&amp;gt;{\mathcal P}_{W,b} := \{ n: Wn+b \in {\mathcal P} \}&amp;lt;/math&amp;gt;, where &amp;lt;math&amp;gt;W := \prod_{p \leq w} p&amp;lt;/math&amp;gt; is the product of all primes less than some threshold w, and b is a number coprime to W (in many cases one can just take b=1).  It is a result in elementary number theory that &amp;lt;math&amp;gt;W = \exp((1+o(1))w)&amp;lt;/math&amp;gt;, thus W is of exponential size in w.  If one seeks primes less than N, one must therefore set w no larger than &amp;lt;math&amp;gt;\log N&amp;lt;/math&amp;gt; or so.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The W-trick is a simple trick to remove some of the structure from the set of primes, and also to increase the density of primes slightly.  Basically, instead of looking at the set &amp;lt;math&amp;gt;{\mathcal P} := \{2,3,5,7,\ldots\}&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&amp;lt;/math&amp;gt; &lt;/ins&gt;of primes, one instead looks at the set &amp;lt;math&amp;gt;{\mathcal P}_{W,b} := \{ n: Wn+b \in {\mathcal P} \}&amp;lt;/math&amp;gt;, where &amp;lt;math&amp;gt;W := \prod_{p \leq w} p&amp;lt;/math&amp;gt; is the product of all primes less than some threshold w, and b is a number coprime to W (in many cases one can just take b=1).  It is a result in elementary number theory that &amp;lt;math&amp;gt;W = \exp((1+o(1))w)&amp;lt;/math&amp;gt;, thus W is of exponential size in w.  If one seeks primes less than N, one must therefore set w no larger than &amp;lt;math&amp;gt;\log N&amp;lt;/math&amp;gt; or so.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The set &amp;lt;math&amp;gt;{\mathcal P}_{W,b}&amp;lt;/math&amp;gt; is a little bit denser than the primes; the primes less than N have density about &amp;lt;math&amp;gt;1/\log N&amp;lt;/math&amp;gt; by the prime number theorem, but &amp;lt;math&amp;gt;{\mathcal P}_{W,b}&amp;lt;/math&amp;gt; has density about &amp;lt;math&amp;gt; \frac{W}{\phi(W)} \frac{1}{\log N} \approx \frac{\log w}{\log N}&amp;lt;/math&amp;gt;; raising w to &amp;lt;math&amp;gt;O(\log N)&amp;lt;/math&amp;gt; (which is the largest feasible value), the density of the W-tricked primes thus increases slightly from &amp;lt;math&amp;gt;1/\log N&amp;lt;/math&amp;gt; to about &amp;lt;math&amp;gt;\log \log N / \log N&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The set &amp;lt;math&amp;gt;{\mathcal P}_{W,b}&amp;lt;/math&amp;gt; is a little bit denser than the primes; the primes less than N have density about &amp;lt;math&amp;gt;1/\log N&amp;lt;/math&amp;gt; by the prime number theorem, but &amp;lt;math&amp;gt;{\mathcal P}_{W,b}&amp;lt;/math&amp;gt; has density about &amp;lt;math&amp;gt; \frac{W}{\phi(W)} \frac{1}{\log N} \approx \frac{\log w}{\log N}&amp;lt;/math&amp;gt;; raising w to &amp;lt;math&amp;gt;O(\log N)&amp;lt;/math&amp;gt; (which is the largest feasible value), the density of the W-tricked primes thus increases slightly from &amp;lt;math&amp;gt;1/\log N&amp;lt;/math&amp;gt; to about &amp;lt;math&amp;gt;\log \log N / \log N&amp;lt;/math&amp;gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The W-tricked primes &amp;lt;math&amp;gt;{\mathcal P}_{W,b}&amp;lt;/math&amp;gt; also behave more &amp;#039;pseudorandomly&amp;#039; than the primes themselves.  For instance, the primes are of course highly biased to favour odd numbers over even numbers, but the W-tricked primes have no such bias once w is at least 2 (by the prime number theorem in arithmetic progressions).  More generally, the primes do not equidistribute modulo q for any q, but the W-tricked primes do as soon as w is greater than or equal to all the prime factors of q.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The W-tricked primes &amp;lt;math&amp;gt;{\mathcal P}_{W,b}&amp;lt;/math&amp;gt; also behave more &amp;#039;pseudorandomly&amp;#039; than the primes themselves.  For instance, the primes are of course highly biased to favour odd numbers over even numbers, but the W-tricked primes have no such bias once w is at least 2 (by the prime number theorem in arithmetic progressions).  More generally, the primes do not equidistribute modulo q for any q, but the W-tricked primes do as soon as w is greater than or equal to all the prime factors of q.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Teorth</name></author>
	</entry>
	<entry>
		<id>https://michaelnielsen.org/polymath/index.php?title=W-trick&amp;diff=2198&amp;oldid=prev</id>
		<title>Teorth: New page: The W-trick is a simple trick to remove some of the structure from the set of primes, and also to increase the density of primes slightly.  Basically, instead of looking at the set &lt;math&gt;{...</title>
		<link rel="alternate" type="text/html" href="https://michaelnielsen.org/polymath/index.php?title=W-trick&amp;diff=2198&amp;oldid=prev"/>
		<updated>2009-08-03T18:06:43Z</updated>

		<summary type="html">&lt;p&gt;New page: The W-trick is a simple trick to remove some of the structure from the set of primes, and also to increase the density of primes slightly.  Basically, instead of looking at the set &amp;lt;math&amp;gt;{...&lt;/p&gt;
&lt;p&gt;&lt;b&gt;New page&lt;/b&gt;&lt;/p&gt;&lt;div&gt;The W-trick is a simple trick to remove some of the structure from the set of primes, and also to increase the density of primes slightly.  Basically, instead of looking at the set &amp;lt;math&amp;gt;{\mathcal P} := \{2,3,5,7,\ldots\}$ of primes, one instead looks at the set &amp;lt;math&amp;gt;{\mathcal P}_{W,b} := \{ n: Wn+b \in {\mathcal P} \}&amp;lt;/math&amp;gt;, where &amp;lt;math&amp;gt;W := \prod_{p \leq w} p&amp;lt;/math&amp;gt; is the product of all primes less than some threshold w, and b is a number coprime to W (in many cases one can just take b=1).  It is a result in elementary number theory that &amp;lt;math&amp;gt;W = \exp((1+o(1))w)&amp;lt;/math&amp;gt;, thus W is of exponential size in w.  If one seeks primes less than N, one must therefore set w no larger than &amp;lt;math&amp;gt;\log N&amp;lt;/math&amp;gt; or so.&lt;br /&gt;
&lt;br /&gt;
The set &amp;lt;math&amp;gt;{\mathcal P}_{W,b}&amp;lt;/math&amp;gt; is a little bit denser than the primes; the primes less than N have density about &amp;lt;math&amp;gt;1/\log N&amp;lt;/math&amp;gt; by the prime number theorem, but &amp;lt;math&amp;gt;{\mathcal P}_{W,b}&amp;lt;/math&amp;gt; has density about &amp;lt;math&amp;gt; \frac{W}{\phi(W)} \frac{1}{\log N} \approx \frac{\log w}{\log N}&amp;lt;/math&amp;gt;; raising w to &amp;lt;math&amp;gt;O(\log N)&amp;lt;/math&amp;gt; (which is the largest feasible value), the density of the W-tricked primes thus increases slightly from &amp;lt;math&amp;gt;1/\log N&amp;lt;/math&amp;gt; to about &amp;lt;math&amp;gt;\log \log N / \log N&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
The W-tricked primes &amp;lt;math&amp;gt;{\mathcal P}_{W,b}&amp;lt;/math&amp;gt; also behave more &amp;#039;pseudorandomly&amp;#039; than the primes themselves.  For instance, the primes are of course highly biased to favour odd numbers over even numbers, but the W-tricked primes have no such bias once w is at least 2 (by the prime number theorem in arithmetic progressions).  More generally, the primes do not equidistribute modulo q for any q, but the W-tricked primes do as soon as w is greater than or equal to all the prime factors of q.&lt;/div&gt;</summary>
		<author><name>Teorth</name></author>
	</entry>
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