login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A012166 arctanh(tan(arcsinh(x))) = x+3/3!*x^3+49/5!*x^5+1915/7!*x^7+143905/9!*x^9... 0
1, 3, 49, 1915, 143905, 17011475, 2994791825, 719040113675, 229441987074625, 92824148885459875, 46824601078366320625, 28633111489683067566875, 20964654070778933185750625, 18047023186844734022903421875 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

FORMULA

a(n) ~ (2*n)! * 2^(2*n+1) * exp((2*n+1)*Pi/4) / (exp(Pi/2)-1)^(2*n+1). - Vaclav Kotesovec, Oct 30 2013

MATHEMATICA

Table[n!*SeriesCoefficient[ArcTanh[Tan[ArcSinh[x]]], {x, 0, n}], {n, 1, 40, 2}] (* Vaclav Kotesovec, Oct 30 2013 *)

CROSSREFS

Sequence in context: A012206 A012094 A012059 * A012068 A012126 A203513

Adjacent sequences:  A012163 A012164 A012165 * A012167 A012168 A012169

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 29 13:17 EST 2021. Contains 349416 sequences. (Running on oeis4.)