A009731 Expansion of tan(x)*cosh(log(1+x)).

0, 1, 0, 5, -12, 96, -480, 3968, -29568, 283840, -2759040, 31139712, -369431040, 4852567552, -67622790144, 1018594276352, -16267048304640, 277008597516288, -4982377179119616, 94730142262034432, -1894021067538432000

Offset

0,4

Links

Table of n, a(n) for n=0..20.

Formula

a(n) ~ n! * (-1)^(n+1) * tan(1) / 2. - Vaclav Kotesovec, Jan 23 2015

Mathematica

CoefficientList[Series[((1 + (1 + x)^2)*Tan[x])/(2*(1 + x)), {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 23 2015 *)
With[{nn=30}, CoefficientList[Series[Tan[x]*Cosh[Log[1+x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, May 05 2018 *)

Crossrefs

Sequence in context: A009414 A009426 A304001 * A009427 A267271 A009754

Adjacent sequences: A009728 A009729 A009730 * A009732 A009733 A009734

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

First previous Mathematica program replaced by Harvey P. Dale, May 05 2018

Status

approved