OFFSET
1,1
LINKS
Eric Weisstein's World of Mathematics, Centered Triangular Number
FORMULA
8*a(n) = 10+3*A097269(n). - R. J. Mathar, Jul 26 2017
MATHEMATICA
nmax = 300; f[x_] := Sum[x^(3 k (k - 1)/2 + 1), {k, 1, 20}]^2; Exponent[#, x] & /@ List @@ Normal[Series[f[x], {x, 0, nmax}]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Jun 03 2017
STATUS
approved