A277490 - OEIS

%I #9 Nov 10 2017 07:37:32

%S -1,0,2,12,72,520,5040,67284,1156736,23655888,549676800,14216252380,

%T 405068387328,12624364306008,427599019108352,15646376279614500,

%U 615155126821355520,25861820048469628576,1157706908035331457024,54977324662490442177708,2760439046217459138560000

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

%H G. C. Greubel, <a href="/A277490/b277490.txt">Table of n, a(n) for n = 0..385</a>

%F a(n) ~ n^(n-1) / 2.

%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.

%K sign

%O 0,3

%A _Vaclav Kotesovec_, Oct 17 2016