A157570 Half the number of length n integer sequences with sum zero and sum of squares 2888.

1, 9, 114, 11430, 928665, 57312801, 2929653363, 133959064275, 6012597282660, 258520740868390, 10793900036914731, 439085564014381089, 17106142080255638592, 634240156516816014270, 22487281301691416873070

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,0,2888)/2.

Crossrefs

Sequence in context: A356240 A379522 A157551 * A223499 A362774 A157233

Adjacent sequences: A157567 A157568 A157569 * A157571 A157572 A157573

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved