A009158 Expansion of cosh(tan(tan(x))).

1, 1, 17, 673, 48033, 5387009, 871869745, 192177458593, 55316788832065, 20139680768683777, 9044546204411462737, 4909707244721993221025, 3168104630099094560839393, 2396238201505538217521920001

Offset

0,3

Links

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

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Cosh[Tan[Tan[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Aug 18 2024 *)

Crossrefs

Sequence in context: A063941 A089018 A118769 * A012050 A012157 A012137

Adjacent sequences: A009155 A009156 A009157 * A009159 A009160 A009161

Keyword

nonn

Author

R. H. Hardin

Extensions

Extended and signs tested Mar 15 1997 by Olivier Gérard.

Previous Mathematica program replaced by Harvey P. Dale, Aug 18 2024

Status

approved