A157591 Half the number of length n integer sequences with sum zero and sum of squares 6962.

1, 3, 354, 35410, 3079815, 254391501, 20017977868, 1645049437956, 130713839323245, 9274041450918255, 602446992143570574, 36862449524697504786, 2161188475320550751257, 122528449769743353508305

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,0,6962)/2.

Crossrefs

Sequence in context: A209426 A037302 A341229 * A005336 A062226 A266454

Adjacent sequences: A157588 A157589 A157590 * A157592 A157593 A157594

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved