OFFSET
0,2
FORMULA
a(n) ~ (2*n)! * (-1)^(n+1) / (n * r^(2*n)), where r = 0.82560766907116185156994603327818731... is the root of the equation cos(r) = tanh(r). - Vaclav Kotesovec, Jan 23 2015
MATHEMATICA
Log[ 1+Tanh[ x ]*Sin[ x ] ] (* Even Part *)
nn = 20; Table[(CoefficientList[Series[Log[1 + Sin[x]*Tanh[x]], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* Vaclav Kotesovec, Jan 23 2015 *)
CROSSREFS
KEYWORD
sign
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
STATUS
approved