A157547 Half the number of length n integer sequences with sum zero and sum of squares 450.

1, 3, 126, 2170, 37335, 921333, 21967484, 466292604, 9161931075, 164162481681, 2705726857350, 41747317681290, 619096670144225, 8923605271290360, 124998845674120920, 1699006653803990456, 22382667992161145863

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,0,450)/2.

Crossrefs

Sequence in context: A114877 A152859 A241647 * A160879 A157562 A324152

Adjacent sequences: A157544 A157545 A157546 * A157548 A157549 A157550

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved