A157556 Half the number of length n integer sequences with sum zero and sum of squares 1152.

1, 3, 18, 3010, 166725, 8371713, 307008163, 8869151172, 244109996040, 6625340217595, 174712060895757, 4452494561526960, 108958868923534266, 2551477805087525055, 57187304932168982070, 1233918981730653994884

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,0,1152)/2.

Crossrefs

Sequence in context: A291078 A335181 A297536 * A214442 A057133 A321249

Adjacent sequences: A157553 A157554 A157555 * A157557 A157558 A157559

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved