OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..100
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
KEYWORD
nonn
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
EXTENSIONS
Edited by D. S. McNeil, Dec 17 2011
STATUS
approved