A277500 E.g.f.: -LambertW(-tan(x)).
0, 1, 2, 11, 80, 821, 10608, 167215, 3105024, 66433129, 1609025024, 43521156755, 1300287942656, 42528924900125, 1511407185512448, 57992816331075511, 2389444376908726272, 105219795048784564945, 4931495123285481881600, 245105773365008603770907
Offset: 0
Keywords
Links
- Robert Israel, Table of n, a(n) for n = 0..384
Programs
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Maple
S:= series(-LambertW(-tan(x)),x,31): seq(coeff(S,x,n)*n!,n=0..30); # Robert Israel, Mar 09 2017
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Mathematica
CoefficientList[Series[-LambertW[-Tan[x]], {x, 0, 20}], x] * Range[0, 20]! -
PARI
x='x+O('x^50); concat([0], Vec(serlaplace(-lambertw(-tan(x))))) \\ G. C. Greubel, Nov 07 2017
Formula
a(n) ~ sqrt(1+exp(-2)) * arctan(exp(-1))^(1/2-n) * exp(1/2-n) * n^(n-1).