A012149 sech(tan(sin(x)))=1-1/2!*x^2+1/4!*x^4+47/6!*x^6-447/8!*x^8...

1, -1, 1, 47, -447, -31649, 1241153, 94750991, -10593064063, -734072274241, 217167723689345, 9078987118530031, -9048136095510326335, 132977311200029875999, 677245929952843206843329

Offset

0,4

Links

Table of n, a(n) for n=0..14.

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Sech[Tan[Sin[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Sep 16 2016 *)

Crossrefs

Sequence in context: A142454 A200954 A126300 * A106104 A009086 A034779

Adjacent sequences: A012146 A012147 A012148 * A012150 A012151 A012152

Keyword

sign

Author

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

Status

approved