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A157592
Half the number of length n integer sequences with sum zero and sum of squares 7200.
1
1, 3, 126, 23870, 2725455, 314174553, 29749465207, 2182715679324, 150186806030400, 10125676123572801, 666260841650613825, 42448715774998807794, 2597948199840416316530, 152089661374768398565935
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,0,7200)/2.
CROSSREFS
Sequence in context: A157562 A324152 A274314 * A213988 A159319 A086154
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 02 2009
STATUS
approved