A012148 Expansion of e.g.f. sec(tan(sin(x))), even powers only.

1, 1, 9, 153, 4337, 188049, 11533497, 947095529, 100391885153, 13337306468001, 2164609458010345, 420395208704497849, 96150102074339268945, 25560738902667056074801, 7807205800461246020523161, 2710746396065167779192263433, 1059485323408621763305666629825

Offset

0,3

Links

Table of n, a(n) for n=0..16.

Example

1+1/2!*x^2+9/4!*x^4+153/6!*x^6+4337/8!*x^8...

Mathematica

With[{nn=40}, Take[CoefficientList[Series[Sec[Tan[Sin[x]]], {x, 0, nn}], x]Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Dec 23 2011 *)

Crossrefs

Sequence in context: A113391 A045755 A009037 * A193540 A193543 A374854

Adjacent sequences: A012145 A012146 A012147 * A012149 A012150 A012151

Keyword

nonn

Author

Patrick Demichel

Extensions

More terms from Harvey P. Dale, Dec 23 2011

Name edited by Michel Marcus, Aug 25 2025

Status

approved