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A024257
Expansion of tanh(tan(x)*x)/2.
1
0, 1, 4, -72, -5632, -161920, 18173952, 4194147328, 310213328896, -84365860995072, -39813939519815680, -5549928926785306624, 2813587774502929956864, 2234702652489178135134208, 497733049858403607865458688
OFFSET
0,3
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Tanh[Tan[x]*x]/2 , {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Apr 27 2016 *)
CROSSREFS
Cf. A009817.
Sequence in context: A076744 A177392 A158269 * A152653 A344693 A172478
KEYWORD
sign
AUTHOR
EXTENSIONS
Extended with signs Mar 1997
Prior Mathematica program deleted by Harvey P. Dale, Apr 27 2016
STATUS
approved