Doubly recursive sequence

[Christian G. Bower]

Leroy Quet <qqquet at mindspring.com> wrote:
...
> Interesting. 
> 
> I am slightly curious about such things such as: 
> for which indexes k, does a[k] = 1,
> or when is a[k] < a[k-1] ?
> 
> And what would be the sequence of differences between consecutive k's, 
> where
> a[k] < a[k-1]?
> 
> 
> (The k's where a[k] = 1 are 0, 1, 4, and 64, for k < 100 {as seen from 
> the list generated by Farideh Firoozbakht}. These k's, except the 0, all 
> happen to be powers of 2; but this is much too small a sample to deduce 
> anything, obviously.)

I get 400 and 489 as the next 1's of a[k]. Although my calculations can
overflow. I don't believe they did in this case, but I'd have to spend
a little time verifying it to make sure.