A157584 Half the number of length n integer sequences with sum zero and sum of squares 5408.

1, 9, 90, 17270, 2392575, 203322273, 14072688875, 881578169937, 54028224275760, 3177868465756435, 181594395820598805, 10109617693345774539, 538976083520642296074, 27345902242485061861185, 1326768997661185039512750

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,0,5408)/2.

Crossrefs

Sequence in context: A157545 A274953 A157558 * A077334 A020243 A239867

Adjacent sequences: A157581 A157582 A157583 * A157585 A157586 A157587

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved