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A009808
Expansion of tanh(tan(tan(x))).
0
1, 2, 8, -400, -54016, -6545408, -886739968, -130488590336, -17561155108864, -157860190420992, 1926815267611213824, 1659729586864045162496, 1201487932870410723393536, 858251595734608746586832896
OFFSET
0,2
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Tanh[Tan[Tan[x]]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Jun 12 2016 *)
CROSSREFS
Sequence in context: A219994 A014185 A367998 * A035129 A284603 A329685
KEYWORD
sign
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
Prior Mathematica program replaced by Harvey P. Dale, Jun 12 2016
STATUS
approved