OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
FORMULA
G.f.: (1/(1 - x)) * Sum_{k>=1} x^(k^3)/(1 - x^k).
MATHEMATICA
f[n_] := DivisorSum[n, 1 &, # <= n^(1/3) &]; Accumulate @ Array[f, 100] (* Amiram Eldar, Sep 04 2021 *)
PROG
(PARI) N=99; x='x+O('x^N); Vec(sum(k=1, N^(1/3), x^k^3/(1-x^k))/(1-x))
(PARI) a(n) = sum(k=1, n, sumdiv(k, d, d^3<=k)); \\ Michel Marcus, Sep 05 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Sep 04 2021
STATUS
approved