A157552 Half the number of length n integer sequences with sum zero and sum of squares 800.

1, 3, 42, 3410, 143445, 4303761, 117586819, 2875510809, 67804504560, 1524258428187, 33435072500775, 715914503534022, 14685555146992730, 286576099225123995, 5347457520977926782, 96148425385860533358

Offset

2,2

Links

R. H. Hardin, Table of n, a(n) for n=2..50

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,0,800)/2.

Crossrefs

Sequence in context: A083402 A145984 A213956 * A058808 A155210 A157572

Adjacent sequences: A157549 A157550 A157551 * A157553 A157554 A157555

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved