A157585 Half the number of length n integer sequences with sum zero and sum of squares 5618.

1, 3, 330, 27570, 2233965, 165759111, 11709395180, 864416336904, 61700500723635, 3932420281395045, 229474040212588578, 12613127103936869874, 664285970637825836755, 33831654295810674426165, 1673010760008675643666440

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,0,5618)/2.

Crossrefs

Sequence in context: A235334 A160070 A112895 * A045645 A245190 A005335

Adjacent sequences: A157582 A157583 A157584 * A157586 A157587 A157588

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved