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A157567
Half the number of length n integer sequences with sum zero and sum of squares 2450.
1
1, 9, 378, 13330, 689715, 30934071, 1463659596, 72481823352, 3407856306435, 142400570465307, 5478965101306950, 198874787418398598, 6919440283487706065, 232730571288134765160, 7599816260357477794632, 241028324482889751669040
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,0,2450)/2.
CROSSREFS
Sequence in context: A238561 A290574 A218714 * A157593 A157602 A124042
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 02 2009
STATUS
approved