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%I #6 Aug 01 2023 17:08:50
%S 1,9,114,3810,103185,2729181,69340908,1835068068,46949243445,
%T 1072699180795,22440539853666,442180822802082,8348531623530553,
%U 152424934237053765,2702148696449820840,46523455154624265192
%N Half the number of length n integer sequences with sum zero and sum of squares 722.
%H R. H. Hardin, <a href="/A157551/b157551.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,0,722)/2.
%K nonn
%O 2,2
%A _R. H. Hardin_, Mar 02 2009
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