A157541 Half the number of length n integer sequences with sum zero and sum of squares 162.

1, 3, 54, 610, 7575, 124005, 1721692, 21584676, 254430555, 2752913955, 27276416970, 252510790038, 2245919946361, 19423497389310, 163254969718200, 1331429118674408, 10524020807274019, 80607360684092143, 599129356328684230

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,0,162)/2.

Crossrefs

Sequence in context: A174782 A345074 A119294 * A374522 A182159 A065102

Adjacent sequences: A157538 A157539 A157540 * A157542 A157543 A157544

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved