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E.g.f.: -1/(1-LambertW(-x))^2.
4

%I #19 Jun 02 2019 05:38:30

%S -1,2,-2,6,8,170,1872,29246,519808,10698642,248787200,6458737142,

%T 185138721792,5808233422394,197952647108608,7283047491096750,

%U 287705410381709312,12145740050403520034,545696709922799419392,25998534614835587104742,1309210567403228200960000

%N E.g.f.: -1/(1-LambertW(-x))^2.

%H G. C. Greubel, <a href="/A277510/b277510.txt">Table of n, a(n) for n = 0..385</a>

%F a(n) ~ n^(n-1) / 4.

%t CoefficientList[Series[-1/(1-LambertW[-x])^2, {x, 0, 20}], x] * Range[0, 20]!

%o (PARI) x='x+O('x^50); Vec(serlaplace(-1/(1 - lambertw(-x))^2)) \\ _G. C. Greubel_, Nov 08 2017

%Y Cf. A063170, A134095, A277458, A277490, A308506.

%K sign

%O 0,2

%A _Vaclav Kotesovec_, Oct 18 2016