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A342628 a(n) = Sum_{d|n} d^(n-d). 6
1, 2, 2, 6, 2, 45, 2, 322, 731, 3383, 2, 132901, 2, 827641, 10297068, 33570818, 2, 2578617270, 2, 44812807567, 678610493340, 285312719189, 2, 393061010002613, 95367431640627, 302875123369471, 150094917726535604, 569939345952661545, 2, 105474306078445349841, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..599

FORMULA

G.f.: Sum_{k>=1} x^k/(1 - (k * x)^k).

If p is prime, a(p) = 2.

MATHEMATICA

a[n_] := DivisorSum[n, #^(n - #) &]; Array[a, 30] (* Amiram Eldar, Mar 17 2021 *)

PROG

(PARI) a(n) = sumdiv(n, d, d^(n-d));

(PARI) my(N=40, x='x+O('x^N)); Vec(sum(k=1, N, x^k/(1-(k*x)^k)))

CROSSREFS

Cf. A023887, A062796, A308594, A342629.

Sequence in context: A293216 A319708 A230266 * A329380 A348146 A344007

Adjacent sequences:  A342625 A342626 A342627 * A342629 A342630 A342631

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Mar 16 2021

STATUS

approved

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Last modified May 24 14:18 EDT 2022. Contains 354037 sequences. (Running on oeis4.)