A012431 - OEIS

A012431

sech(arctan(x)*sin(x)) = 1-12/4!*x^4+360/6!*x^6-7280/8!*x^8...

1, 0, -12, 360, -7280, -383040, 89394624, -8970625664, -316692862720, 470941672802304, -146844936720038912, 18279034160407939072, 9932590980055055503360, -8395139128320596309032960

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

LINKS

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

MATHEMATICA

With[{nn=30}, Take[CoefficientList[Series[Sech[ArcTan[x]Sin[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Aug 28 2017 *)

CROSSREFS

Sequence in context: A074094 A012553 A128043 * A012386 A130213 A012633

Adjacent sequences: A012428 A012429 A012430 * A012432 A012433 A012434

KEYWORD

sign

AUTHOR

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

STATUS

approved