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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A009182 Expansion of cosh(x)/cos(tan(x)). 0
1, 2, 20, 608, 34320, 3084640, 405224896, 73292662784, 17468683774208, 5306511481924096, 2001393333656871936, 917626310129679884288, 502654675782900203720704, 324215069803278031144280064 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
FORMULA
a(n) ~ (2*n)! * 8 * cosh(arctan(Pi/2)) / ((4+Pi^2) * arctan(Pi/2)^(2*n+1)). - Vaclav Kotesovec, Jan 22 2015
MATHEMATICA
Cosh[ x ]/Cos[ Tan[ x ] ] (* Even Part *)
nn = 20; Table[(CoefficientList[Series[Cosh[x]*Sec[Tan[x]], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* Vaclav Kotesovec, Jan 22 2015 *)
CROSSREFS
Sequence in context: A275779 A292415 A197743 * A015207 A054941 A012495
KEYWORD
nonn
AUTHOR
EXTENSIONS
Extended and signs tested Mar 15 1997 by Olivier Gérard.
STATUS
approved

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 24 14:46 EDT 2024. Contains 374584 sequences. (Running on oeis4.)