OFFSET
0,3
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..10000
FORMULA
G.f.: Sum_{n>=1} q^(n*(n-1)) / (1-q)^n.
MATHEMATICA
nmax = 60; CoefficientList[Series[Sum[x^(k*(k-1))/(1-x)^k, {k, 1, Sqrt[nmax] + 1}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Nov 11 2018 *)
PROG
(PARI) N=66; q='q+O('q^N); Vec( sum(n=1, N, q^(n*(n-1))/(1-q)^n) )
CROSSREFS
KEYWORD
nonn
AUTHOR
Joerg Arndt, Nov 11 2018
STATUS
approved