This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A009110 Expansion of e.g.f. cos(x)/cosh(tan(x)), even powers only. 1
 1, -2, 4, 32, 400, -3680, -719168, -45313024, -1201882880, 190738937344, 41876315935744, 3729103532367872, -442609357053390848, -294584246423093633024, -75554765797484141625344, -7698772402123265223688192, 3712165683571701387680088064 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS G. C. Greubel, Table of n, a(n) for n = 0..243 MATHEMATICA With[{nn=40}, Take[CoefficientList[Series[Cos[x]/Cosh[Tan[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, May 06 2016 *) PROG (PARI) x='x+O('x^50); v=Vec(serlaplace(cos(x)/cosh(tan(x)))); vector(#v\2, n, v[2*n-1]) \\ G. C. Greubel, Jul 26 2018 CROSSREFS Sequence in context: A085055 A075070 A144937 * A225170 A134958 A101460 Adjacent sequences:  A009107 A009108 A009109 * A009111 A009112 A009113 KEYWORD sign AUTHOR EXTENSIONS Extended with signs by Olivier Gérard, Mar 15 1997 More terms from and prior Mathematica program replaced by Harvey P. Dale, May 06 2016 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.

Last modified December 9 03:27 EST 2019. Contains 329872 sequences. (Running on oeis4.)