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!)
A012641 tanh(arcsinh(x)*cos(x))=x-6/3!*x^3+120/5!*x^5-6216/7!*x^7... 1
1, -6, 120, -6216, 548544, -74860544, 14571230336, -3827313412352, 1304171528695808, -559299942314340352, 294737591597024591872, -187195194238509459439616, 141014910901971840963870720 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 0..218

FORMULA

a(n) ~ c * (-1)^n * (2*n)! * n / r^(2*n), where r = 0.8922083063567712426146182695087047187586345275404... is the root of the equation arcsin(r)*cosh(r) = Pi/2, c = 1.175488110258... . - Vaclav Kotesovec, Feb 04 2015

MATHEMATICA

nn = 20; Table[(CoefficientList[Series[Tanh[ArcSinh[x]*Cos[x]], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* Vaclav Kotesovec, Feb 04 2015 *)

CROSSREFS

Sequence in context: A002370 A012846 A331640 * A012795 A054479 A012475

Adjacent sequences:  A012638 A012639 A012640 * A012642 A012643 A012644

KEYWORD

sign

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 28 04:31 EST 2021. Contains 349400 sequences. (Running on oeis4.)