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%I #17 Jan 10 2025 18:41:04
%S 0,1,-1,7,-26,165,-1216,10827,-111376,1316585,-17441536,257028847,
%T -4164440576,73616009805,-1409649350656,29070305745267,
%U -642306123237376,15137914082015825,-379068323095576576,10050622525103392087
%N Expansion of e.g.f.: log(1+tan(x)*cosh(x)).
%F a(n) ~ (n-1)! * (-1)^(n+1) / r^n, where r = 0.678886646361824692174613333109767742222867349... is the root of the equation cosh(r)*tan(r) = 1. - _Vaclav Kotesovec_, Jan 24 2015
%t With[{nn=20},CoefficientList[Series[Log[1+Tan[x]Cosh[x]],{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Jan 10 2025 *)
%t CoefficientList[Series[Log[1 + Cosh[x]*Tan[x]], {x, 0, 20}], x] * Range[0, 20]! (* _Vaclav Kotesovec_, Jan 24 2015 *)
%K sign,easy
%O 0,4
%A _R. H. Hardin_
%E Extended with signs by _Olivier Gérard_, Mar 15 1997
%E Definition clarified and first Mathematica program replaced by _Harvey P. Dale_, Jan 10 2025