A012645 sech(arcsinh(x)*cos(x))=1-1/2!*x^2+21/4!*x^4-765/6!*x^6+53193/8!*x^8...

1, -1, 21, -765, 53193, -6008025, 993328413, -226691205013, 68261145008657, -26216583047151921, 12507068079360896165, -7255577391165958142893, 5029681350011635244424921, -4106028806747521109741788425

Offset

0,3

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sech[ArcSinh[x]Cos[x]], {x, 0, nn}], x] Range[ 0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, May 15 2022 *)

Crossrefs

Sequence in context: A143002 A062755 A012850 * A220069 A028469 A295845

Adjacent sequences: A012642 A012643 A012644 * A012646 A012647 A012648

Keyword

sign

Author

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

Status

approved