a(n) = sigma_2(a(n-1)): 10|a(n>3) ?

[Max Alekseyev]

Zak,

I think, it's a tough question.
An affirmative answer to your question would imply, in particular,
that in this sequence there are no squares (since a term following a
square in this sequence is odd). But existence of squares in this
sequence is a hard question by itself, I believe.

Regards,
Max

On Wed, May 14, 2008 at 12:09 AM, zak seidov <zakseidov at yahoo.com> wrote:
> Rule:
> a(n>1)=sigma_2(a(n-1)) with a(1)=2.
> SEQ starts:
> 2,5,26,850,943950.
> My Q:
> Are all next terms divisible by 10?
> thanks, zak
>
>
>
>
>