A157542 Half the number of length n integer sequences with sum zero and sum of squares 200.

1, 3, 42, 930, 17685, 265041, 3668483, 44840097, 529728300, 5955342987, 65311345275, 699155920398, 7170690213960, 69964606094670, 652763403442422, 5868431782886486, 51137730082075059, 433379839761592641

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,0,200)/2.

Crossrefs

Sequence in context: A366006 A366010 A206820 * A078601 A268621 A218308

Adjacent sequences: A157539 A157540 A157541 * A157543 A157544 A157545

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved