A012145 sech(arcsin(arctanh(x)))=1-1/2!*x^2-7/4!*x^4-169/6!*x^6-9199/8!*x^8...

1, -1, -7, -169, -9199, -915441, -146524599, -34565815257, -11286151088991, -4868161148587617, -2677533017865604839, -1826930427561513127305, -1513046625847449915823695, -1494316021415982844933350225

Offset

0,3

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sech[ArcSin[ArcTanh[x]]], {x, 0, nn}], x] Range[ 0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, May 05 2022 *)

Crossrefs

Sequence in context: A162131 A258299 A012067 * A368839 A351154 A005019

Adjacent sequences: A012142 A012143 A012144 * A012146 A012147 A012148

Keyword

sign

Author

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

Status

approved