%I A157546
%S A157546 1,9,54,1290,47385,1080891,19941831,335927439,5541820740,87714576070,
%T A157546 1349748111657,20228679068676,290345411571852,3966279413712840,
%U A157546 51810189395306490,652108043960695984,7955418278826810531
%N A157546 Half the number of length n integer sequences with sum zero and sum of 
               squares 392.
%H A157546 Ron Hardin, <a href="b157546.txt">Table of n, a(n) for n=2..50</a>
%F A157546 [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,0,392)/2.
%Y A157546 Sequence in context: A037704 A093847 A157539 this_sequence A157560 A157588 
               A058849
%Y A157546 Adjacent sequences: A157543 A157544 A157545 this_sequence A157547 A157548 
               A157549
%K A157546 nonn
%O A157546 2,2
%A A157546 Ron Hardin (rhhardin(AT)att.net) Mar 02 2009