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A012240 -log(cos(tan(x)))=1/2!*x^2+10/4!*x^4+232/6!*x^6+10064/8!*x^8... 3

%I

%S 1,10,232,10064,720384,78009600,11977120768,2480763381760,

%T 666957211828224,225809770695098368,93981332166180077568,

%U 47151835657444566499328,28061010401657661222289408

%N -log(cos(tan(x)))=1/2!*x^2+10/4!*x^4+232/6!*x^6+10064/8!*x^8...

%H Vincenzo Librandi, <a href="/A012240/b012240.txt">Table of n, a(n) for n = 0..100</a>

%F a(n) ~ 2*(2*n+1)! / arctan(Pi/2)^(2*n+2). - _Vaclav Kotesovec_, Jun 26 2014

%t With[{nn=30},Take[CoefficientList[Series[-Log[Cos[Tan[x]]],{x,0,nn}],x] Range[0,nn]!,{3,-1,2}]] (* _Harvey P. Dale_, Jun 25 2014 *)

%Y Bisection of A009329 and A009387.

%K nonn

%O 0,2

%A Patrick Demichel (patrick.demichel(AT)hp.com)

%E Edited by _D. S. McNeil_, Dec 17 2011

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Last modified October 16 20:35 EDT 2019. Contains 328103 sequences. (Running on oeis4.)