login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A012152 arctanh(tan(tan(x)))=x+6/3!*x^3+176/5!*x^5+12240/7!*x^7... 0
1, 6, 176, 12240, 1561088, 318007808, 94807748608, 38942692972544, 21088169713729536, 14558790290337431552, 12481351528273319821312, 13009249833253480856289280, 16200881782506627598590672896 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

FORMULA

a(n) ~ (2*n)! / (arctan(Pi/4))^(2*n+1). - Vaclav Kotesovec, Feb 05 2015

MATHEMATICA

nn = 20; Table[(CoefficientList[Series[ArcTanh[Tan[Tan[x]]], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* Vaclav Kotesovec, Feb 05 2015 *)

CROSSREFS

Sequence in context: A024277 A012177 A012227 * A165928 A024278 A062240

Adjacent sequences:  A012149 A012150 A012151 * A012153 A012154 A012155

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 August 25 05:45 EDT 2019. Contains 326323 sequences. (Running on oeis4.)