A157598 Half the number of length n integer sequences with sum zero and sum of squares 8712.

1, 3, 198, 27930, 3388365, 475265259, 48238917727, 3831384879156, 290324159283540, 21674347016566915, 1571698374562433667, 110138942653526323056, 7411777323163714916688, 477289870722013730288040

Offset

2,2

Links

R. H. Hardin, Table of n, a(n) for n=2..50

Formula

[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,0,8712)/2.

Crossrefs

Sequence in context: A256407 A256406 A157565 * A023310 A054701 A356178

Adjacent sequences: A157595 A157596 A157597 * A157599 A157600 A157601

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved