The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A012717 arctanh(arctanh(x)*exp(x))=x+2/2!*x^2+7/3!*x^3+36/4!*x^4+293/5!*x^5... 0

%I #10 Nov 28 2016 19:56:00

%S 0,1,2,7,36,293,2710,31099,408072,6199465,105183658,1990233551,

%T 41337728300,937722749325,23029648705726,609300643351555,

%U 17268619403747600,522102791124578001,16771008730706230098

%N arctanh(arctanh(x)*exp(x))=x+2/2!*x^2+7/3!*x^3+36/4!*x^4+293/5!*x^5...

%F a(n) ~ (n-1)!/(2*(tanh(r/2))^n), where r = 1.17812663495672544... is the root of the equation r*exp((exp(r)-1)/(exp(r)+1)) = 2. - _Vaclav Kotesovec_, Oct 24 2013

%t CoefficientList[Series[ArcTanh[ArcTanh[x]*Exp[x]], {x, 0, 20}], x]* Range[0, 20]! (* _Vaclav Kotesovec_, Oct 24 2013 *)

%K nonn

%O 0,3

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

%E Prepended missing a(0)=0, _Vaclav Kotesovec_, Oct 24 2013

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 13 04:06 EDT 2024. Contains 375113 sequences. (Running on oeis4.)