%I #6 Jan 20 2024 16:18:12
%S 1,9,342,26670,1960515,199230213,17543249724,1392949344564,
%T 103992753869385,7125947800456375,447172658110001142,
%U 26218227869348323614,1476897053364550626991,80893894777513364496600
%N Half the number of length n integer sequences with sum zero and sum of squares 6498.
%H R. H. Hardin, <a href="/A157589/b157589.txt">Table of n, a(n) for n=2..50</a>
%F [cache enabling] count(n,s,ss)->count(n,t,tt) where t=s mod n, q=(t-s)/n, tt=ss+2*q*s+n*q^2; count(n,t,tt)=sum[i^2<=tt]{ count(n-1,t-i,tt-i^2) }. a(n)=count(n,0,6498)/2.
%K nonn
%O 2,2
%A _R. H. Hardin_, Mar 02 2009