%I A157579
%S A157579 1,3,294,21630,1556655,102426933,6421722076,420393758436,26609856588945,
%T A157579 1503958534048245,77827209776501394,3793522397195559678,
%U A157579 177172760525971961023,8001788984919141620040,350900981113969220953080
%N A157579 Half the number of length n integer sequences with sum zero and sum of 
               squares 4418.
%H A157579 Ron Hardin, <a href="b157579.txt">Table of n, a(n) for n=2..50</a>
%F A157579 [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,0,4418)/2.
%Y A157579 Sequence in context: A058455 A116532 A124357 this_sequence A104821 A119065 
               A119069
%Y A157579 Adjacent sequences: A157576 A157577 A157578 this_sequence A157580 A157581 
               A157582
%K A157579 nonn
%O A157579 2,2
%A A157579 Ron Hardin (rhhardin(AT)att.net) Mar 02 2009