A157589 Half the number of length n integer sequences with sum zero and sum of squares 6498.

1, 9, 342, 26670, 1960515, 199230213, 17543249724, 1392949344564, 103992753869385, 7125947800456375, 447172658110001142, 26218227869348323614, 1476897053364550626991, 80893894777513364496600

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,0,6498)/2.

Crossrefs

Sequence in context: A354689 A098652 A110695 * A055601 A225328 A203745

Adjacent sequences: A157586 A157587 A157588 * A157590 A157591 A157592

Keyword

nonn

Author

R. H. Hardin, Mar 02 2009

Status

approved