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A157541
Half the number of length n integer sequences with sum zero and sum of squares 162.
1
1, 3, 54, 610, 7575, 124005, 1721692, 21584676, 254430555, 2752913955, 27276416970, 252510790038, 2245919946361, 19423497389310, 163254969718200, 1331429118674408, 10524020807274019, 80607360684092143, 599129356328684230
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,0,162)/2.
CROSSREFS
Sequence in context: A174782 A345074 A119294 * A374522 A182159 A065102
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 02 2009
STATUS
approved