A009197 Expansion of exp(log(1+x)/cosh(x)).

1, 1, 0, -3, -6, 35, 135, -476, -6300, 14349, 298515, 254056, -26673042, -26975169, 1931306377, 16803854768, -336040323112, -1435742838615, 20743481564487, 843925791375728, -11354618863953550, -37784454009996005

Offset: 0

Author

R. H. Hardin

Keywords

• sign
• easy

Links

• Vaclav Kotesovec, Table of n, a(n) for n = 0..200

Programs

Mathematica

CoefficientList[Series[Exp[Log[1+x]/Cosh[x]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jul 02 2015 *)

Formula

a(n) ~ n! * (-1)^n / (GAMMA(-1/cosh(1)) * n^(1+1/cosh(1))). - Vaclav Kotesovec, Jul 02 2015

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997