A157583 Half the number of length n integer sequences with sum zero and sum of squares 5202.

1, 3, 306, 19110, 1405335, 127596189, 10056226796, 714714066732, 47739604854315, 2926869332706055, 164336205885920178, 8620987583406297606, 434508999474316043459, 21294115220098361584440, 1014206441760046027667880

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,0,5202)/2.

Crossrefs

Sequence in context: A052505 A307020 A071525 * A218361 A085319 A123032

Adjacent sequences: A157580 A157581 A157582 * A157584 A157585 A157586

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved