A363646 Expansion of Sum_{k>0} (1/(1 - (k*x)^k)^2 - 1).

2, 11, 58, 565, 6256, 95762, 1647094, 33752329, 774919720, 20029303030, 570623341234, 17838801038274, 605750213184520, 22226048320465666, 875787902918124708, 36894332593824661521, 1654480523772673528372, 78693266840741507386757

Offset

1,1

Links

Table of n, a(n) for n=1..18.

Formula

a(n) = Sum_{d|n} (n/d)^n * (d+1).

Mathematica

a[n_] := DivisorSum[n, (n/#)^n * (# + 1) &]; Array[a, 20] (* Amiram Eldar, Jul 17 2023 *)

Prog

(PARI) a(n) = sumdiv(n, d, (n/d)^n*(d+1));

Crossrefs

Cf. A023887, A338663, A363647, A363648.

Cf. A007503, A362683.

Sequence in context: A241103 A162771 A020057 * A210646 A054564 A280674

Adjacent sequences: A363643 A363644 A363645 * A363647 A363648 A363649

Keyword

nonn

Author

Seiichi Manyama, Jun 13 2023

Status

approved