[go: up one dir, main page]

login
A157559
Half the number of length n integer sequences with sum zero and sum of squares 1458.
1
1, 3, 162, 5470, 204405, 10044237, 418371436, 15735232164, 556455670755, 18061671242945, 536877862194894, 14910514196745102, 397858116730316515, 10322446421549098305, 260281325962170069480, 6368185576937692717552
OFFSET
2,2
LINKS
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: A173128 A377253 A157440 * A157586 A341224 A042439
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 02 2009
STATUS
approved