OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..385
FORMULA
L.g.f.: -log(Product_{k>=1} (1 - k*x^k)^(k^(k-1))) = Sum_{k>=1} a(k)*x^k/k. - Seiichi Manyama, Jun 09 2019
G.f.: Sum_{k>0} k^(k+1) * x^k / (1 - k * x^k). - Seiichi Manyama, Jan 11 2023
MATHEMATICA
sd[n_]:=Total[#^(#+n/#)&/@Divisors[n]]; Array[sd, 20] (* Harvey P. Dale, Mar 28 2021 *)
PROG
(PARI) a(n) = sumdiv(n, d, d^(d+n/d));
(PARI) N=20; x='x+O('x^N); Vec(x*deriv(-log(prod(k=1, N, (1-k*x^k)^(k^(k-1)))))) \\ Seiichi Manyama, Jun 09 2019
(PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=1, N, k^(k+1)*x^k/(1-k*x^k))) \\ Seiichi Manyama, Jan 11 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 12 2017
STATUS
approved