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A013184
exp(arctanh(x)+tanh(x)) = 1+2*x+4/2!*x^2+8/3!*x^3+16/4!*x^4+72/5!*x^5...
0
1, 2, 4, 8, 16, 72, 544, 3936, 25344, 193920, 1920384, 21876736, 246359040, 2967878656, 39508168704, 589063146496, 9120978370560, 149737853943808, 2587275558617088, 48291040167362560, 939278027083448320
OFFSET
0,2
FORMULA
a(n) ~ 2*exp(tanh(1)) * n^n/exp(n) = 2*exp((exp(2)-1)/(exp(2)+1)) * n^n/exp(n). - Vaclav Kotesovec, Oct 24 2013
MATHEMATICA
With[{nn=20}, CoefficientList[Series[Exp[ArcTanh[x]+Tanh[x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Jul 24 2011 *)
CROSSREFS
Sequence in context: A322037 A013133 A012997 * A066713 A004000 A374732
KEYWORD
nonn
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
STATUS
approved