A157557 Half the number of length n integer sequences with sum zero and sum of squares 1250.

1, 3, 222, 7810, 245715, 7887621, 271336828, 9598223664, 323149486005, 9653120522639, 265199107509930, 6875831133411318, 170878889034103705, 4105071237469192095, 95749849725794169816, 2169082695217727013712

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,0,1250)/2.

Crossrefs

Sequence in context: A140441 A261385 A071881 * A279532 A157582 A241098

Adjacent sequences: A157554 A157555 A157556 * A157558 A157559 A157560

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved