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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
1, 10, 232, 10064, 720384, 78009600, 11977120768, 2480763381760, 666957211828224, 225809770695098368, 93981332166180077568, 47151835657444566499328, 28061010401657661222289408
OFFSET
0,2
LINKS
FORMULA
a(n) ~ 2*(2*n+1)! / arctan(Pi/2)^(2*n+2). - Vaclav Kotesovec, Jun 26 2014
MATHEMATICA
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 *)
CROSSREFS
Bisection of A009329 and A009387.
Sequence in context: A239773 A087434 A297648 * A295410 A188679 A167867
KEYWORD
nonn
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
EXTENSIONS
Edited by D. S. McNeil, Dec 17 2011
STATUS
approved