A277490 E.g.f.: -1/(1+LambertW(-x)^2).

-1, 0, 2, 12, 72, 520, 5040, 67284, 1156736, 23655888, 549676800, 14216252380, 405068387328, 12624364306008, 427599019108352, 15646376279614500, 615155126821355520, 25861820048469628576, 1157706908035331457024, 54977324662490442177708, 2760439046217459138560000

Offset

0,3

Links

G. C. Greubel, Table of n, a(n) for n = 0..385

Formula

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

Mathematica

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

Prog

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

Crossrefs

Cf. A063170, A134095.

Sequence in context: A052556 A371039 A052833 * A296975 A144086 A358064

Adjacent sequences: A277487 A277488 A277489 * A277491 A277492 A277493

Keyword

sign

Author

Vaclav Kotesovec, Oct 17 2016

Status

approved