The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A012843 tan(sec(x)*arctanh(x))=x+7/3!*x^3+185/5!*x^5+11471/7!*x^7... 1
 1, 7, 185, 11471, 1263185, 215079159, 52220520521, 17117211436287, 7278847910698529, 3895256097472909671, 2561265786122546675545, 2029572906879775183011503, 1907361016227301624675795825 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Vaclav Kotesovec, Table of n, a(n) for n = 0..200 Vaclav Kotesovec, Graph - abs(e.g.f.) in the complex plane FORMULA a(n) ~ 4 * cos(r) * (2*n+1)! / ((2/(1-r^2) + Pi*sin(r)) * r^(2*n+2)), where r = 0.7989151684962902269091787502961348455829847186615330217492... is the root of the equation sec(r)*arctanh(r) = Pi/2. - Vaclav Kotesovec, Feb 07 2015 MATHEMATICA nn = 20; Table[(CoefficientList[Series[Tan[ArcTanh[x]*Sec[x]], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* Vaclav Kotesovec, Feb 07 2015 *) CROSSREFS Sequence in context: A217244 A152436 A176338 * A012798 A297765 A193811 Adjacent sequences: A012840 A012841 A012842 * A012844 A012845 A012846 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 26 21:09 EDT 2024. Contains 372844 sequences. (Running on oeis4.)