OFFSET
0,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: Product_{k>0} f(q^k) where f(q) = Product_{i>=1} (1 + i*q^i).
G.f.: Product_{k>0} Product_{d|k} (1 + d*x^k).
MATHEMATICA
m = 38; CoefficientList[Series[Product[1 + i*x^(i*j), {i, 1, m}, {j, 1, m}], {x, 0, m}], x] (* Amiram Eldar, Aug 23 2020 *)
PROG
(PARI) N=40; x='x+O('x^N); Vec(prod(i=1, N, prod(j=1, N\i, 1+i*x^(i*j))))
(PARI) N=40; x='x+O('x^N); Vec(prod(k=1, N, prod(d=1, k, 1+(k%d==0)*d*x^k)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Aug 23 2020
STATUS
approved