login
A157572
Half the number of length n integer sequences with sum zero and sum of squares 3200.
1
1, 3, 42, 13330, 1149525, 68923281, 3762973571, 184036492377, 8678968080840, 390210773279547, 17118756925603575, 733096379424490302, 30076017737894907870, 1173815703627064565445, 43806372065182513944702
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,0,3200)/2.
CROSSREFS
Sequence in context: A157552 A058808 A155210 * A332973 A137192 A253577
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 02 2009
STATUS
approved