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A157540 Half the number of length n integer sequences with sum zero and sum of squares 128. 1

%I

%S 1,3,6,430,8775,114681,1213471,11685663,110201400,997307245,

%T 8767514811,75092781699,615909156954,4807634283375,35885733707970,

%U 258099905201634,1799253706774203,12198525957520155,80576646822300850,518883888358457370

%N Half the number of length n integer sequences with sum zero and sum of squares 128.

%H R. H. Hardin, <a href="/A157540/b157540.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,0,128)/2.

%K nonn

%O 2,2

%A _R. H. Hardin_ Mar 02 2009

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Last modified August 12 07:45 EDT 2022. Contains 356067 sequences. (Running on oeis4.)