OFFSET
1,2
COMMENTS
Sum of divisors d of n such that n/d is a cube.
Inverse Moebius transform of A078429.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..20000
FORMULA
a(n) = Sum_{d|n} A078429(d).
D.g.f.: zeta(s-1)*zeta(3s). - R. J. Mathar, Jun 05 2020
Sum_{k=1..n} a(k) ~ Pi^6 * n^2 / 1890. - Vaclav Kotesovec, May 20 2021
MATHEMATICA
nmax = 75; CoefficientList[Series[Sum[x^(k^3)/(1 - x^(k^3))^2, {k, 1, Floor[nmax^(1/3)] + 1}], {x, 0, nmax}], x] // Rest
a[n_] := DivisorSum[n, # &, IntegerQ[(n/#)^(1/3)] &]; Table[a[n], {n, 1, 75}]
PROG
(PARI) A327626(n) = sumdiv(n, d, ispower(n/d, 3)*d); \\ Antti Karttunen, Sep 19 2019
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
Ilya Gutkovskiy, Sep 19 2019
STATUS
approved