A009355 - OEIS

%I #13 Jun 22 2015 22:19:50

%S 0,1,-1,0,-4,40,-181,896,-8464,88320,-863041,9382912,-120330244,

%T 1676579840,-24638823301,390142722048,-6678730634944,121851014348800,

%U -2353418855768161,48123147849826304,-1039698070255280164

%N Expansion of log(1+sinh(x))/cosh(x).

%F a(n) ~ (n-1)! * (-1)^(n+1) / (sqrt(2) * (log(1+sqrt(2)))^n). - _Vaclav Kotesovec_, Jan 23 2015

%t Log[ 1+Sinh[ x ] ]/Cosh[ x ]

%t CoefficientList[Series[Log[1 + Sinh[x]]*Sech[x], {x, 0, 20}], x] * Range[0, 20]! (* _Vaclav Kotesovec_, Jan 23 2015 *)

%K sign,easy

%O 0,5

%A _R. H. Hardin_

%E Extended with signs by _Olivier Gérard_, Mar 15 1997