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A157565 Half the number of length n integer sequences with sum zero and sum of squares 2178. 1

%I

%S 1,3,198,9310,376485,22631679,1141749532,52484724372,2266995222285,

%T 89935056097975,3267564223225962,110915350947910158,

%U 3617265650971040159,114705568549182973950,3535047653641613917560,105710505247924746059104

%N Half the number of length n integer sequences with sum zero and sum of squares 2178.

%H R. H. Hardin, <a href="/A157565/b157565.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,0,2178)/2.

%K nonn

%O 2,2

%A _R. H. Hardin_ Mar 02 2009

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Last modified August 12 04:25 EDT 2022. Contains 356067 sequences. (Running on oeis4.)