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%I A157580 #6 Apr 11 2022 13:10:46
%S A157580 1,3,18,11970,1334085,133955073,9824277155,567625941444,
%T A157580 31246085767560,1696086845812315,89452573267087437,
%U A157580 4559354532659814420,223147765159835078290,10450853058701142231795,468478402281324084911670
%N A157580 Half the number of length n integer sequences with sum zero and sum of squares 4608.
%H A157580 R. H. Hardin, <a href="/A157580/b157580.txt">Table of n, a(n) for n=2..50</a>
%F A157580 [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,0,4608)/2.
%K A157580 nonn
%O A157580 2,2
%A A157580 _R. H. Hardin_, Mar 02 2009

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