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A157577
Half the number of length n integer sequences with sum zero and sum of squares 4050.
1
1, 3, 378, 18910, 992325, 74527005, 5338966892, 339980231676, 20037272191665, 1077068920503015, 53256851208061050, 2465137614876120834, 109671118311748056245, 4742369931941953806600, 199288535032516918383432
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,0,4050)/2.
CROSSREFS
Sequence in context: A068988 A136025 A370448 * A062604 A160192 A304424
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 02 2009
STATUS
approved