A157569 Half the number of length n integer sequences with sum zero and sum of squares 2738.

1, 9, 234, 13330, 759255, 39386151, 1941592492, 100065421116, 4986199986795, 221853806154915, 9037873481632974, 346801773380423010, 12750860059402207015, 453349862010556020825, 15650738757439717731720

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,0,2738)/2.

Crossrefs

Sequence in context: A276536 A288683 A302914 * A279492 A297747 A211052

Adjacent sequences: A157566 A157567 A157568 * A157570 A157571 A157572

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved