This site is supported by donations to The OEIS Foundation.

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 4500 articles have referenced us, often saying "we would not have discovered this result without the OEIS".

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A009842 Expansion of tanh(x)/cosh(log(1+x)). 0
 0, 1, 0, -5, 12, 6, -120, 442, -2352, 13192, 53280, -1665432, 12223200, -6629648, -706340544, 9387463888, -95898673920, 563447710848, 8308014488064, -283290718941056, 3505513923832320, -9173243369732864, -499029405102412800 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS FORMULA a(n) ~ n! * (2*cos(3*n*Pi/4)*(1 - exp(4) - 2*exp(2)*sin(2)) + 2*(1 - exp(4) + 2*exp(2)*sin(2))*sin(3*n*Pi/4)) / ((1 + exp(4) + 2*exp(2)*cos(2)) * 2^(1+n/2)). - Vaclav Kotesovec, Jan 24 2015 MATHEMATICA Tanh[ x ]/Cosh[ Log[ 1+x ] ] CoefficientList[Series[(2*(1 + x)*Tanh[x])/(1 + (1 + x)^2), {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 24 2015 *) CROSSREFS Sequence in context: A022835 A022834 A046610 * A169729 A070368 A066326 Adjacent sequences:  A009839 A009840 A009841 * A009843 A009844 A009845 KEYWORD sign,easy AUTHOR EXTENSIONS Extended with signs by Olivier Gérard, Mar 15 1997 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .