A012642 - OEIS

A012642

arctanh(arcsinh(x)*cos(x))=x-2/3!*x^3-32/5!*x^5+152/7!*x^7+48448/9!*x^9...

1, -2, -32, 152, 48448, 289408, -393649024, -34249082624, 12871254335488, 2591959365570560, -694262452828553216, -534293242711984668672, 97599429997759939117056, 140451121892184627503628288

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

LINKS

Table of n, a(n) for n=0..13.

FORMULA

a(n) ~ (-1)^n * cosh(1) * 2^(2*n+3) * n^(2*n) / ((4+Pi^2*cosh(1)^2) * exp(2*n)). - Vaclav Kotesovec, Nov 01 2013

MATHEMATICA

With[{nn=30}, Take[CoefficientList[Series[ArcTanh[ArcSinh[x]Cos[x]], {x, 0, nn}], x]Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Oct 20 2012 *)

CROSSREFS

Sequence in context: A123105 A123287 A236550 * A244730 A169833 A228582

Adjacent sequences: A012639 A012640 A012641 * A012643 A012644 A012645

KEYWORD

sign

AUTHOR

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

STATUS

approved