A012202 sech(arctan(arcsin(x)))=1-1/2!*x^2+9/4!*x^4-249/6!*x^6+11953/8!*x^8...

1, -1, 9, -249, 11953, -992401, 115133433, -19289685193, 4104153335777, -1154213252748193, 390283459641717353, -165544701587974757145, 81456402896849322863505, -48584594120969426596224305

Offset

0,3

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sech[ArcTan[ArcSin[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Apr 08 2018 *)

Crossrefs

Sequence in context: A367541 A300757 A289551 * A012098 A012072 A007408

Adjacent sequences: A012199 A012200 A012201 * A012203 A012204 A012205

Keyword

sign

Author

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

Status

approved