A009288 Expansion of exp(x)/cos(log(1+x)).

1, 1, 2, 1, 11, -39, 356, -3023, 30841, -349979, 4422846, -61445339, 931259427, -15288729819, 270290509256, -5119527465219, 103428161877041, -2220041987184023, 50453882091213146, -1210316349687219159

Offset

0,3

Links

Table of n, a(n) for n=0..19.

Formula

a(n) ~ n! * exp(-1 + exp(-Pi/2)) / ((exp(Pi/2)-1) * (exp(-Pi/2)-1)^n). - Vaclav Kotesovec, Jan 22 2015

Mathematica

Exp[ x ]/Cos[ Log[ 1+x ] ]
CoefficientList[Series[E^x*Sec[Log[1 + x]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 22 2015 *)

Crossrefs

Sequence in context: A012904 A013015 A012900 * A322513 A082272 A107049

Adjacent sequences: A009285 A009286 A009287 * A009289 A009290 A009291

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved