A009317 - OEIS

%I #17 Jun 21 2015 21:49:01

%S 0,1,-2,4,-23,183,-1459,13592,-153348,1975117,-28287606,449154660,

%T -7849907559,149555531331,-3083839320171,68448665226744,

%U -1627353764342224,41258541219292569,-1111163801421888834

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

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

%t With[{nn=20},CoefficientList[Series[Log[1+Log[1+x]]/Cosh[x],{x,0,nn}], x]Range[0,nn]!] (* _Harvey P. Dale_, Jan 23 2012 *)

%K sign,easy

%O 0,3

%A _R. H. Hardin_

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