A157573 Half the number of length n integer sequences with sum zero and sum of squares 3362.

1, 3, 246, 17230, 1034445, 59305701, 3243926588, 185256960120, 10229264210745, 504340200498475, 22766981281651398, 968060807776968126, 39440547846380819957, 1553885734839506217555, 59443252831855326838200

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,0,3362)/2.

Crossrefs

Sequence in context: A092799 A229690 A140163 * A082717 A157777 A318065

Adjacent sequences: A157570 A157571 A157572 * A157574 A157575 A157576

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved