A009431 Expansion of log(1+x)/cosh(sin(x)).

0, 1, -1, -1, 0, 49, -165, -393, -504, 70785, -434385, -517265, -12647976, 654552625, -6276987717, 18362076327, -636272644560, 22683808563841, -312594994151361, 2817355930176479, -72112751626318640, 2222078368780722865

Offset: 0

Author

R. H. Hardin

Keywords

• sign
• easy

Programs

Mathematica

Log[ 1+x ]/Cosh[ Sin[ x ] ]
CoefficientList[Series[Log[1 + x]*Sech[Sin[x]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 23 2015 *)

Formula

a(n) ~ (n-1)! * (-1)^(n+1) / cosh(sin(1)). - Vaclav Kotesovec, Jan 23 2015

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997