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

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A009684 Expansion of tan(sinh(x))/cos(x) (odd powers only). 0
 1, 6, 92, 2744, 135568, 10052064, 1046433728, 145777470848, 26210435272960, 5912584665282048, 1635801299492215808, 544795386333006067712, 215040848214192589017088, 99279916831031214863081472 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS FORMULA a(n) ~ (2*n-1)! * 4 / (sqrt(4+Pi^2) * cos(arcsinh(Pi/2)) * arcsinh(Pi/2)^(2*n)). - Vaclav Kotesovec, Jan 23 2015 MATHEMATICA Tan[ Sinh[ x ]]/Cos[ x ] (* Odd Part *) nn = 20; Table[(CoefficientList[Series[Sec[x]*Tan[Sinh[x]], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* Vaclav Kotesovec, Jan 23 2015 *) CROSSREFS Sequence in context: A280214 A113266 A009607 * A221080 A009527 A053512 Adjacent sequences: A009681 A009682 A009683 * A009685 A009686 A009687 KEYWORD nonn AUTHOR EXTENSIONS Extended and signs tested Mar 15 1997 by Olivier Gérard. Offset changed to 1 by Vaclav Kotesovec, Jan 23 2015 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 December 3 13:34 EST 2022. Contains 358524 sequences. (Running on oeis4.)