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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A012029 E.g.f.: sech(sin(arctan(x))) (even powers only). 1
 1, -1, 17, -721, 56993, -7232161, 1344866225, -344599447921, 116382225519425, -50097660050713921, 26773024797675332945, -17392081348966913859601, 13497082647397365780254177 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..50 FORMULA a(n) ~ (-1)^n * 2^(2*n+5) * n^(2*n+1/2) * (Pi^2+4)^(n-1) / (exp(2*n) * Pi^(2*n+1/2)). - Vaclav Kotesovec, Nov 08 2013 EXAMPLE sech(sin(arctan(x))) = 1 -1/2!*x^2 +17/4!*x^4 -721/6!*x^6 +56993/8!*x^8 ... MATHEMATICA With[{nn=30}, Take[CoefficientList[Series[Sech[Sin[ArcTan[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Oct 03 2013 *) CROSSREFS Sequence in context: A309410 A201311 A012182 * A012193 A128274 A012085 Adjacent sequences: A012026 A012027 A012028 * A012030 A012031 A012032 KEYWORD sign 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 March 29 14:52 EDT 2023. Contains 361599 sequences. (Running on oeis4.)