A009681 Expansion of tan(sinh(x))*exp(x).

0, 1, 2, 6, 16, 72, 288, 1904, 10368, 89344, 610304, 6445824, 52885504, 660602880, 6324756480, 91175548928, 997700468736, 16301080281088, 200677417680896, 3664597991424000, 50126593037172736, 1011727950085619712

Offset

0,3

Links

Table of n, a(n) for n=0..21.

Formula

a(n) ~ n! * (1 + (-1)^(n+1) + (1 + (-1)^n)*Pi/sqrt(4+Pi^2)) / (log((Pi + sqrt(4 + Pi^2))/2))^(n+1). - Vaclav Kotesovec, Jan 23 2015

Mathematica

Tan[ Sinh[ x ] ]*Exp[ x ]
CoefficientList[Series[E^x*Tan[Sinh[x]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 23 2015 *)

Crossrefs

Sequence in context: A121749 A009386 A009605 * A009186 A009328 A009346

Adjacent sequences: A009678 A009679 A009680 * A009682 A009683 A009684

Keyword

nonn,easy

Author

R. H. Hardin

Extensions

Extended and signs tested Mar 15 1997 by Olivier Gérard.

Status

approved