A012826 cos(sec(x)*arcsinh(x))=1-1/2!*x^2-7/4!*x^4-145/6!*x^6-2063/8!*x^8...

1, -1, -7, -145, -2063, -128705, 5154217, -510686033, 254809389793, -27371394484993, 18728499608356185, -5038330344345849489, 3197858289863468529361, -1630641802209014177997505

Offset

0,3

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Cos[Sec[x]ArcSinh[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Aug 04 2018 *)

Crossrefs

Sequence in context: A163028 A367527 A296684 * A232363 A102059 A064624

Adjacent sequences: A012823 A012824 A012825 * A012827 A012828 A012829

Keyword

sign

Author

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

Status

approved