OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..384
FORMULA
G.f.: Sum_{k>0} k^(k+2)*x^k/(1-(k*x)^k).
L.g.f.: -log(Product_{k>=1} (1 - (k*x)^k)^k) = Sum_{k>=1} a(k)*x^k/k. - Seiichi Manyama, Jun 02 2019
MATHEMATICA
Table[Total[Divisors[n]^(n+2)], {n, 20}] (* Harvey P. Dale, Dec 23 2023 *)
PROG
(PARI) {a(n) = sigma(n, n+2)}
(PARI) N=66; x='x+O('x^N); Vec(sum(k=1, N, k^(k+2)*x^k/(1-(k*x)^k)))
(PARI) N=20; x='x+O('x^N); Vec(x*deriv(-log(prod(k=1, N, (1-(k*x)^k)^k)))) \\ Seiichi Manyama, Jun 02 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 09 2017
STATUS
approved