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A157580
Half the number of length n integer sequences with sum zero and sum of squares 4608.
1
1, 3, 18, 11970, 1334085, 133955073, 9824277155, 567625941444, 31246085767560, 1696086845812315, 89452573267087437, 4559354532659814420, 223147765159835078290, 10450853058701142231795, 468478402281324084911670
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,0,4608)/2.
CROSSREFS
Sequence in context: A057133 A321249 A001999 * A101293 A227882 A189799
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 02 2009
STATUS
approved