A336990 - OEIS

A336990

Expansion of Product_{k>=1} 1/(1 - x^k / (1 - k*x)).

1, 1, 3, 8, 22, 62, 182, 560, 1822, 6316, 23467, 93762, 402989, 1858904, 9165303, 48065800, 266791060, 1560140592, 9573440644, 61431041813, 411006873603, 2859978776644, 20653331408062, 154494203986783, 1195107012223439, 9546189429869925, 78632580076861376, 667111706008969377

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..27.

FORMULA

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

MATHEMATICA

m = 27; CoefficientList[Series[Product[1/(1 - x^k/(1 - k*x)), {k, 1, m}], {x, 0, m}], x] (* Amiram Eldar, Aug 10 2020 *)

PROG

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

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