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

[M. F. Hasler]

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