A157559 Half the number of length n integer sequences with sum zero and sum of squares 1458.

1, 3, 162, 5470, 204405, 10044237, 418371436, 15735232164, 556455670755, 18061671242945, 536877862194894, 14910514196745102, 397858116730316515, 10322446421549098305, 260281325962170069480, 6368185576937692717552

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,0,1458)/2.

Crossrefs

Sequence in context: A302950 A173128 A157440 * A157586 A341224 A042439

Adjacent sequences: A157556 A157557 A157558 * A157560 A157561 A157562

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved