A "doublely-recursive" sequence

[Edwin Clark]

On Sun, 3 Aug 2003 f.firoozbakht at sci.ui.ac.ir wrote:

> 
> 
>  The k's where a[k]= 1 are 0,1,4,64,400,489,519,2164,3589 and 8703 for
>  k < 48000.!!
> 
> 


Just finished checking out to 10^5. Here are the values of k such that
a[k] = 1 in this range:

   0, 1, 4, 64, 400, 489, 519, 2164, 3589, 8703, 84761

It is interesting that the last number 84761 is prime. At Neil's
suggestion I will add this to the EIS.

Edwin