A157564 Half the number of length n integer sequences with sum zero and sum of squares 2048.

1, 3, 6, 6830, 561735, 29360121, 1242596383, 47858305311, 1805644314360, 65361758855305, 2298374956416891, 78740814179665443, 2583344854373884146, 80658838456091971635, 2408249945284962451650, 69283128843699421305698

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,0,2048)/2.

Crossrefs

Sequence in context: A071106 A157548 A134901 * A122182 A276701 A157596

Adjacent sequences: A157561 A157562 A157563 * A157565 A157566 A157567

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved