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%I A157557 #4 Mar 31 2012 12:35:25
%S A157557 1,3,222,7810,245715,7887621,271336828,9598223664,323149486005,
%T A157557 9653120522639,265199107509930,6875831133411318,170878889034103705,
%U A157557 4105071237469192095,95749849725794169816,2169082695217727013712
%N A157557 Half the number of length n integer sequences with sum zero and sum of squares 1250.
%H A157557 R. H. Hardin, <a href="/A157557/b157557.txt">Table of n, a(n) for n=2..50</a>
%F A157557 [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,0,1250)/2.
%K A157557 nonn
%O A157557 2,2
%A A157557 _R. H. Hardin_ Mar 02 2009

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