A012110 sech(arcsin(sinh(x)))=1-1/2!*x^2-3/4!*x^4-21/6!*x^6-1543/8!*x^8...

1, -1, -3, -21, -1543, -139241, -17567883, -3247844861, -820544875023, -270409929116881, -112752402237298963, -58042577464009155301, -36153625550535244615703, -26800108152000698851560121

Offset

0,3

Links

Table of n, a(n) for n=0..13.

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sech[ArcSin[Sinh[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Mar 19 2020 *)

Crossrefs

Sequence in context: A290766 A290872 A365497 * A265637 A054739 A117508

Adjacent sequences: A012107 A012108 A012109 * A012111 A012112 A012113

Keyword

sign

Author

Patrick Demichel (patrick.demichel(AT)hp.com)

Status

approved