[seqfan] Re: Odd integers n such that Lucas(n) == 2 (mod n)

[Allan Wechsler]

It seems to me that there are quite a few possibilities for sequences of
this kind. The granddaddy of this concept is  http://oeis.org/A023172 but
also see the surprisingly dense http://oeis.org/A023162.



On Wed, Oct 2, 2019 at 12:56 PM Giovanni Resta <g.resta at iit.cnr.it> wrote:

> The only thing I can say is a(4) = 237040185477.
>
> Giovanni
>
>
> Il 1 Ottobre 2019 11:18:38 CEST, Trizen <trizenx at gmail.com> ha scritto:
> >Hello SeqFans,
> >
> >I would like to share a pretty strange sequence: odd integers n such
> >that
> >Lucas(n) == 2 (mod n), where Lucas(n) is the n-th Lucas number given by
> >A000032(n).
> >
> >Equivalently: odd integers n such that A213060(n) = 2.
> >
> >The first three terms are: 1643, 387997, 174819237.
> >
> >It's quite surprising that these numbers are so rare.
> >
> >Some questions:
> >- Is there anything known about this sequence?
> >- In particular, is this sequence infinite?
> >- Is it worth submitting to OEIS?
> >
> >Thank you,
> >Daniel Suteu
> >
> >--
> >Seqfan Mailing list - http://list.seqfan.eu/
>
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