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E.g.f.: -1/((1-LambertW(-x))*(1+x)).
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%I #7 Nov 10 2017 07:38:14

%S -1,2,-4,15,-44,385,-294,32473,280120,8528049,170757910,4748977321,

%T 132530188308,4210910824393,142940443542274,5273270156096265,

%U 208276214340505456,8800344095155520353,395536292522024420142,18853858817276143333321,949787282108877829653580

%N E.g.f.: -1/((1-LambertW(-x))*(1+x)).

%H G. C. Greubel, <a href="/A277508/b277508.txt">Table of n, a(n) for n = 0..385</a>

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

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

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

%Y Cf. A277507, A277509.

%K sign

%O 0,2

%A _Vaclav Kotesovec_, Oct 18 2016