A009760 Expansion of e.g.f. tan(x)/cosh(log(1+x)).

0, 1, 0, -1, 12, -34, 120, 146, -2352, 23848, -53280, -371768, 12223200, -107535440, 706340544, 2599870352, -95898673920, 1486560431744, -8308014488064, -67260673442176, 3505513923832320, -54539552924497664, 499029405102412800

Offset

0,5

Links

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

Example

a(n) ~ n! * ((1 - exp(4))*cos((1/4)*(1 + 3*n)*Pi) - 2*exp(2)*sin(2)*sin((1/4)*(1 + 3*n)*Pi)) / ((1 + exp(4) + 2*exp(2)*cos(2)) * 2^((n-1)/2)). - Vaclav Kotesovec, Jan 24 2015

Mathematica

With[{nn=30}, CoefficientList[Series[Tan[x]/Cosh[Log[1+x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Nov 13 2011 *)
CoefficientList[Series[(2*(1 + x)*Tan[x])/(1 + (1 + x)^2), {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 24 2015 *)

Prog

(PARI) x='x+O('x^30); concat([0], Vec(serlaplace(tan(x)/cosh(log(1+x))))) \\ G. C. Greubel, Feb 12 2018

Crossrefs

Sequence in context: A296154 A126366 A199114 * A078194 A034510 A083101

Adjacent sequences: A009757 A009758 A009759 * A009761 A009762 A009763

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved