A009186 Expansion of e.g.f.: cosh(x)/exp(tan(x)).

1, -1, 2, -6, 16, -72, 328, -1848, 11712, -81088, 638720, -5318016, 49459840, -483162240, 5159926528, -57865303296, 697030680576, -8815813734400, 118233272496128, -1662921003208704, 24578235697610752, -380141599264751616, 6139851821419921408

Offset

0,3

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Maple

a:= n-> n! * coeff (series (cosh(x)/exp(tan(x)), x, n+1), x, n):
seq (a(n), n=0..30);  # Alois P. Heinz, May 16 2012

Mathematica

With[{nn=30}, CoefficientList[Series[Cosh[x]/Exp[Tan[x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, May 16 2012 *)

Crossrefs

Sequence in context: A009386 A009605 A009681 * A009328 A009346 A009367

Adjacent sequences: A009183 A009184 A009185 * A009187 A009188 A009189

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Definition clarified by Harvey P. Dale, May 16 2012

Status

approved