A012679 tan(tanh(x)*arctan(x))=2/2!*x^2-16/4!*x^4+560/6!*x^6-39296/8!*x^8...

2, -16, 560, -39296, 4526848, -774871040, 184332195840, -58099536592896, 23416511012143104, -11741974762852974592, 7167152797622391013376, -5231209742433608374681600, 4498538959739976198689652736

Offset

0,1

Links

Table of n, a(n) for n=0..12.

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Tan[Tanh[x]ArcTan[x]], {x, 0, nn}], x] Range[0, nn]!, {3, -1, 2}]] (* Harvey P. Dale, Jun 16 2017 *)

Crossrefs

Sequence in context: A121271 A013136 A013004 * A012726 A013177 A375209

Adjacent sequences: A012676 A012677 A012678 * A012680 A012681 A012682

Keyword

sign

Author

Patrick Demichel (patrick.demichel(AT)hp.com)

Status

approved