%I #6 Jun 10 2023 13:18:28
%S 1,9,54,18490,3080025,281083131,20455480647,1378645284663,
%T 90798695826120,5747081242763245,353783429708291517,
%U 21210677666294419836,1217797507802900629878,66543379957754376544455
%N Half the number of length n integer sequences with sum zero and sum of squares 6272.
%H R. H. Hardin, <a href="/A157588/b157588.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,0,6272)/2.
%K nonn
%O 2,2
%A _R. H. Hardin_, Mar 02 2009