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%I #13 Jun 22 2015 22:21:45
%S 0,1,-1,6,-22,176,-1192,12240,-122288,1561088,-20588544,318007808,
%T -5193155328,94807748608,-1841205505024,38942692972544,
%U -875204314126336,21088169713729536,-537861879179575296,14558790290337431552
%N Expansion of log(1+tan(tan(x))).
%F a(n) ~ (n-1)! * (-1)^(n+1) / (arctan(Pi/4))^n. - _Vaclav Kotesovec_, Jan 23 2015
%t Log[ 1+Tan[ Tan[ x ] ] ]
%t CoefficientList[Series[Log[1 + Tan[Tan[x]]], {x, 0, 20}], x] * Range[0, 20]! (* _Vaclav Kotesovec_, Jan 23 2015 *)
%K sign,easy
%O 0,4
%A _R. H. Hardin_
%E Extended with signs by _Olivier Gérard_, Mar 15 1997