A009709 E.g.f. tan(tan(x)/cosh(x)), odd powers only.

1, 1, 17, 593, 19425, 1598177, 158823537, 20206883505, 3739345763009, 800168319488705, 218377697922437073, 71589148444259595281, 27561852243967184213153, 12547454880768646146119585

Offset

1,3

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..100

Example

tan(tan(x)/cosh(x)) = x + 1/6*x^3 + 17/120*x^5 + 593/5040*x^7 + ...

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Tan[Tan[x]/Cosh[x]], {x, 0, nn}], x]Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, May 06 2012 *)

Crossrefs

Sequence in context: A041547 A041544 A202407 * A162490 A296790 A330516

Adjacent sequences: A009706 A009707 A009708 * A009710 A009711 A009712

Keyword

nonn

Author

R. H. Hardin

Extensions

Extended and signs tested Mar 15 1997 by Olivier Gérard.

Status

approved