A157544 Half the number of length n integer sequences with sum zero and sum of squares 288.

1, 3, 18, 770, 20805, 522753, 9593507, 138576324, 1907158560, 25880343115, 341234146077, 4348150676532, 53202598238062, 622919366722485, 6980872709154870, 75312434538456228, 787522030868617855

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,0,288)/2.

Crossrefs

Sequence in context: A070953 A163261 A064846 * A202946 A000853 A065402

Adjacent sequences: A157541 A157542 A157543 * A157545 A157546 A157547

Keyword

nonn

Author

R. H. Hardin, Mar 02 2009

Status

approved