[seqfan] Re: Iterating "smallest odd prime divisor of n^2 + 1"

Neil Sloane njasloane at gmail.com
Mon Nov 6 17:33:55 CET 2017


Maximilian, Thanks!  I just approved the new submissions,

Best regards
Neil

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


On Mon, Nov 6, 2017 at 9:04 AM, M. F. Hasler <seqfan at hasler.fr> wrote:

> On Sat, Nov 4, 2017 at 10:17 AM, Neil Sloane wrote:
>
> > Perhaps there are should be two new sequences (at least):
> >
> > - number of steps to reach either 5 or 13 when starting with n
> > - largest number in the trajectory of n
> >
> > (with a cross-reference to A125256 to make them easy to find)
> >
>
> FWIW I propose
> https://oeis.org/draft/A294656 : Size of the orbit of n under iterations
> of
>  A125256
> https://oeis.org/draft/A294657 : Largest number in the orbit of n under
> iterations of A125256
> in case it's not yet done.
> (I think I will also add A294658 = # steps to reach either 5 or 13,
> which will be equal to the size of the orbit - 1 for almost all n (unless I
> err))
>
> - Maximilian
> <njasloane at gmail.com>
>
>
> On Sat, Nov 4, 2017 at 9:54 AM, Robert Gerbicz <robert.gerbicz at gmail.com>
> wrote:
>
> > Not that nice, all of these converged pretty easily, for example:
> > ? g(4949)
> > 0 4949
> > 1 12246301
> > 2 74985944091301
> > 3 2811445905631859677311936301
> > 4 3952114040147073815012888046973669539943086904940781301
> > 5 101
> > 6 5101
> > 7 13
> > 8 5
>
> --
> Seqfan Mailing list - http://list.seqfan.eu/
>



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