A157597 Half the number of length n integer sequences with sum zero and sum of squares 8450.

1, 9, 630, 48670, 4293525, 358348053, 32224041500, 2966406894648, 259556693304825, 20157653282906667, 1439903350550159550, 97064374251531230622, 6271845201623139087495, 391742584864070048279685

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,0,8450)/2.

Crossrefs

Sequence in context: A188423 A158881 A188394 * A211611 A280904 A210053

Adjacent sequences: A157594 A157595 A157596 * A157598 A157599 A157600

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved