A009374 Expansion of log(1+tan(x))/exp(x).

0, 1, -3, 10, -40, 205, -1287, 9714, -85384, 859889, -9751651, 123102098, -1711387808, 25985945453, -427828028695, 7591346835562, -144408464041712, 2931676572255297, -63262735545686819, 1445955290624608506

Offset: 0

Author

R. H. Hardin

Keywords

• sign
• easy

Programs

Mathematica

Log[ 1+Tan[ x ] ]/Exp[ x ]
CoefficientList[Series[Log[1 + Tan[x]]/E^x, {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 23 2015 *)

Formula

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

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997