A157588 Half the number of length n integer sequences with sum zero and sum of squares 6272.

1, 9, 54, 18490, 3080025, 281083131, 20455480647, 1378645284663, 90798695826120, 5747081242763245, 353783429708291517, 21210677666294419836, 1217797507802900629878, 66543379957754376544455

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,0,6272)/2.

Crossrefs

Sequence in context: A205814 A157546 A157560 * A270575 A058849 A058852

Adjacent sequences: A157585 A157586 A157587 * A157589 A157590 A157591

Keyword

nonn

Author

R. H. Hardin, Mar 02 2009

Status

approved