OFFSET
1,4
MATHEMATICA
f[n_]:=If[Mod[n, 4]==1||Mod[n, 4]==0, Binomial[n (n-1)/2, n (n-1)/4], 0]; Table[f[n], {n, 1, 25}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Geoffrey Critzer, Oct 20 2012
STATUS
approved