[seqfan] Re: A081650

[israel at math.ubc.ca]

>From the program, it seems to be that "(mod k^2)" is being used as a 
function rather than a relation, so even though 52 is congruent to a square 
mod 9 (i.e. 52 == 4^2 mod 9), 52 mod 9 = 7 is not a square.

Since this is an old sequence, I don't think its Data should be changed, 
rather the definition should be clarified. The sequence 2, 5, 13, 52, 241, 
241, 436, 1009, 1009, 1009, ... corresponding to congruence as a relation 
does not seem to be in the OEIS: perhaps you'd like to contribute it.

Cheers,
Robert

On Nov 16 2015, Don Reble wrote:

>Seqfans:
>
> > %S A081650 2,5,13,73,409,801,1584,2241,30601,30601,78409,156825, ...
> > %N A081650 Least nonsquare congruent to i^2 (mod k^2) for all 0<k<=n,
> >            i being any integer.
> > %O A081650 1,1
>
>   Why is a(4)=73, instead of 52?
>
>