OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..152
FORMULA
L.g.f.: -log(Product_{k>=1} (1 - x^k)^(k^(3*k))) = Sum_{k>=1} a(k)*x^k/k. - Seiichi Manyama, Jun 18 2019
EXAMPLE
a(6) = 1^(3+1) + 2^(6+1) + 3^(9+1) + 6^(18+1) = 609359740069674.
MATHEMATICA
f[n_] := Block[{d = Divisors[n]}, Total[d^(3 d + 1)]]; Array[f, 12] (* Robert G. Wilson v, Mar 10 2017 *)
PROG
(PARI) a(n) = sumdiv(n, d, d^(3*d+1)); \\ Michel Marcus, Mar 11 2017
(PARI) N=20; x='x+O('x^N); Vec(x*deriv(-log(prod(k=1, N, (1-x^k)^k^(3*k))))) \\ Seiichi Manyama, Jun 18 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 10 2017
STATUS
approved