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A157576 Half the number of length n integer sequences with sum zero and sum of squares 3872. 1

%I

%S 1,3,66,14630,1446495,105717843,6111518987,323657828739,

%T 16777260176400,835056998169955,40377792647031081,1902059925519314067,

%U 85804943707548960986,3683698658760163764945,151229533594426205964390

%N Half the number of length n integer sequences with sum zero and sum of squares 3872.

%H R. H. Hardin, <a href="/A157576/b157576.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,0,3872)/2.

%K nonn

%O 2,2

%A _R. H. Hardin_ Mar 02 2009

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Last modified October 27 23:01 EDT 2020. Contains 338045 sequences. (Running on oeis4.)