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A009387
Expansion of log(1+tanh(tanh(x))).
1
0, 1, -1, -2, 10, 16, -232, -272, 10064, 7936, -720384, -353792, 78009600, 22368256, -11977120768, -1903757312, 2480763381760, 209865342976, -666957211828224, -29088885112832, 225809770695098368, 4951498053124096
OFFSET
0,4
MATHEMATICA
With[{nn=30}, CoefficientList[Series[Log[1+ Tanh[ Tanh[x]]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Aug 08 2012 *)
CROSSREFS
Cf. A000182.
Bisections are A000182 and A012240.
Sequence in context: A249153 A276046 A268481 * A305093 A316753 A304809
KEYWORD
sign,easy
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
STATUS
approved