A009180 Expansion of cosh(x)/cos(log(1+x)).

1, 0, 2, -3, 23, -130, 1016, -8925, 90369, -1027332, 12980406, -180372995, 2734039527, -44890794078, 793705143908, -15034678005165, 303761462921921, -6520477426903400, 148194700045065674, -3555110881720345347

Offset

0,3

Links

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

Formula

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

Mathematica

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

Crossrefs

Sequence in context: A009130 A093504 A370279 * A359840 A041459 A126702

Adjacent sequences: A009177 A009178 A009179 * A009181 A009182 A009183

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved