[seqfan] Re: On a claim by Chun-Xuan Jiang.

[Neil Sloane]

Please,  instead of saying "This sequence is not in the OEIS",
 always say "This was not in the OEIS but I just added it"!

Neil

On Thu, Mar 15, 2012 at 1:30 PM, Harvey P. Dale <hpd1 at nyu.edu> wrote:

>        This Mma program generates the terms up to 100,000 in just over
> one second:
>
>        Select[Range[100000],And@@PrimeQ/@(#{6,12,18,36,72}+1)&]
>
>        Best,
>
>        Harvey
>
>
> -----Original Message-----
> From: seqfan-bounces at list.seqfan.eu
> [mailto:seqfan-bounces at list.seqfan.eu] On Behalf Of Jack Brennen
> Sent: Thursday, March 15, 2012 1:36 AM
> To: lejeffery7 at gmail.com
> Cc: Sequence Fanatics Discussion list
> Subject: [seqfan] Re: On a claim by Chun-Xuan Jiang.
>
> It's probably infinite, but a proof is probably beyond reach, I'm
> guessing.
>
> The sequence is not in the OEIS.  Values through 10^5:
>
> 1, 121, 380, 506, 511, 3796, 5875, 6006, 8976, 9025, 9186, 10920, 12245,
> 12896, 14476, 14800, 15386, 22451, 23471, 32326, 35175, 38460, 39536,
> 40420, 41456, 43430, 44415, 59901, 60076, 61341, 74676, 76615, 76986,
> 82530, 87390, 99486
>
> On 3/14/2012 10:30 PM, Ed Jeffery wrote:
> > Sorry to post again so soon.
> >
> > In his paper "Disproof of Reimann's Hypothesis," which is supposed to
> > have appeared in Algebras, Groups and Geometries, Vol 21, 2004, see
> > http://vixra.org/pdf/1004.0028v1.pdf (page 10), Chun-Xuan Jiang claims
>
> > that there exist infinitely many integers k such that
> >
> > p1 = 6*k + 1,
> > p2 = 12*k + 1,
> > p3 = 18*k + 1,
> > p4 = 36*k + 1,
> > p5 = 72*k + 1,
> >
> > and p1, p2, p3, p4, p5 are all primes. The numbers n = p1*p2*p3*p4*p5
> > are a class of so-called Carmichael numbers.
> >
> > I tried to calculate the sequence of such k manually but failed, since
>
> > I don't have anything like Mathematica. It is obviously true for k =
> > 1, but I got tired of checking for primality at around k = 85. So I
> wonder:
> >
> > What are the next several values of k?
> >
> > Is the sequence indeed infinite?
> >
> > Is the sequence in the OEIS database?
> >
> > Regards.
> >
> > _______________________________________________
> >
> > Seqfan Mailing list - http://list.seqfan.eu/
> >
> >
>
>
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>
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-- 
Dear Friends, I will soon be retiring from AT&T. New coordinates:

Neil J. A. Sloane, President, OEIS Foundation
11 South Adelaide Avenue, Highland Park, NJ 08904, USA
Phone: 732 828 6098; home page: http://NeilSloane.com
Email: njasloane at gmail.com