Path: csiph.com!weretis.net!feeder4.news.weretis.net!feeder1.news.weretis.net!news.solani.org!.POSTED!not-for-mail From: Thomas 'PointedEars' Lahn Newsgroups: comp.lang.javascript Subject: Re: Primality sieve challenge Date: Mon, 18 Jan 2016 21:37:28 +0100 Organization: PointedEars Software (PES) Lines: 25 Message-ID: <2865358.ifOrN9Bpor@PointedEars.de> References: <5b608a56-e16b-4467-a0ce-4e30f6796920@googlegroups.com> <37264925.IaaGi9xk8D@PointedEars.de> <87ziw27kln.fsf@bsb.me.uk> Reply-To: Thomas 'PointedEars' Lahn Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8Bit X-Trace: solani.org 1453149450 31623 eJwFwYEBACAEBMCVSB7j6Mv+I3TnBgVjw7F9fGbsZsd5N5nBKANKiG5bU35SCnxacpY1XT8tDBFC (18 Jan 2016 20:37:30 GMT) X-Complaints-To: abuse@news.solani.org NNTP-Posting-Date: Mon, 18 Jan 2016 20:37:30 +0000 (UTC) User-Agent: KNode/4.14.2 X-User-ID: eJwNyMkBwCAMA7CVyGk6TmLI/iNQPRWWkoRnpMfEUBe2VJycaN7uLyb/Tb9Ssmkmhz0XWtBjQNMLHC1x1OoHcYkWbg== Cancel-Lock: sha1:5UsiyKv2VWTNfIb3jQ8n/5cwPnY= X-NNTP-Posting-Host: eJwFwQkBwDAIA0BLPIGscgoM/xJ6F56aTWQkYmNbSVn7wTsu6m2Vfng0RneUUpDA9VrIZ4UHC8kQWg== Xref: csiph.com comp.lang.javascript:29328 Ben Bacarisse wrote: > Thomas 'PointedEars' Lahn writes: >> Gene Wirchenko wrote: >>> […] All primes >= 5 are of the form 6k +/- 1 where k is a positive >>> integer. >> Interesting thesis. Prove it. > > It's almost trivial. All integers >= 5 can be written in the form 6k+n > where n is in {-1, 0, 1, ... 4} and k > 0, ACK. > but all those that have the form 6k + {0, 2, 3, 4} are clearly composite. I can see why it is so for {0, 2, 4} (all multiples of 6 are divisible by 2, so are the sums when added 2 or 4), but why also for the summand 3? Also, I do not see how your argument proves Gene’s assertion. -- PointedEars FAQ: | SVN: Twitter: @PointedEars2 | ES Matrix: Please do not cc me. / Bitte keine Kopien per E-Mail.