A009434 Expansion of e.g.f: log(1+x)/cosh(tanh(x)).

0, 1, -1, -1, 0, 69, -225, -1653, 3976, 187401, -965385, -14516745, 61266744, 3032650893, -21187300953, -491788726653, 2947006495920, 166337505847057, -1463633608132017, -46261934493321105, 358635306874354320

Offset

0,6

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Mathematica

With[{nn=20}, CoefficientList[Series[Log[1+x]/Cosh[Tanh[x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Jun 19 2013 *)

Prog

(Magma)
R<x>:=PowerSeriesRing(Rationals(), 30);
[0] cat Coefficients(R!(Laplace( Log(1+x)/Cosh(Tanh(x)) ))); // G. C. Greubel, Sep 06 2023
(SageMath)
def A009434_list(prec):
    P.<x> = PowerSeriesRing(QQ, prec)
    return P( log(1+x)/cosh(tanh(x)) ).egf_to_ogf().list()
A009434_list(40) # G. C. Greubel, Sep 06 2023
(PARI) my(x='x+O('x^30)); concat([0], Vec(serlaplace(log(1+x)/cosh(tanh(x))))) \\ Joerg Arndt, Sep 06 2023

Crossrefs

Cf. A009405 - A009420, A009422 - A009433, A009435 - A009439.

Sequence in context: A153672 A283053 A249899 * A228671 A115920 A183447

Adjacent sequences: A009431 A009432 A009433 * A009435 A009436 A009437

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Definition clarified and prior Mathematica program replaced by Harvey P. Dale, Jun 19 2013

Status

approved