A157599 Half the number of length n integer sequences with sum zero and sum of squares 8978.

1, 9, 402, 44230, 4512465, 423267831, 37803628716, 3527887213476, 318332583745245, 25647872392849575, 1892012326768856754, 131465592083214083058, 8752726227773492626389, 563521423775802944905950

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,0,8978)/2.

Crossrefs

Sequence in context: A012078 A332139 A266924 * A063876 A063156 A058850

Adjacent sequences: A157596 A157597 A157598 * A157600 A157601 A157602

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved