login
A157558
Half the number of length n integer sequences with sum zero and sum of squares 1352.
1
1, 9, 90, 4710, 294975, 12521313, 439040875, 13748247801, 422094067740, 12416563759270, 354721205123505, 9872974834469253, 263171856408106464, 6676220201317388190, 161958493217535635430, 3785772107967822217382
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,0,1352)/2.
CROSSREFS
Sequence in context: A160569 A157545 A274953 * A157584 A077334 A020243
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 02 2009
STATUS
approved