A157579 Half the number of length n integer sequences with sum zero and sum of squares 4418.

1, 3, 294, 21630, 1556655, 102426933, 6421722076, 420393758436, 26609856588945, 1503958534048245, 77827209776501394, 3793522397195559678, 177172760525971961023, 8001788984919141620040, 350900981113969220953080

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,0,4418)/2.

Crossrefs

Sequence in context: A347138 A124357 A212798 * A104821 A282195 A334177

Adjacent sequences: A157576 A157577 A157578 * A157580 A157581 A157582

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved