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A013174 exp(arctanh(x) + arctan(x)) = 1 + 2*x + 4/2!*x^2 + 8/3!*x^3 + 16/4!*x^4 + 80/5!*x^5 +... 0
1, 2, 4, 8, 16, 80, 640, 4160, 21760, 177920, 2291200, 25548800, 223436800, 2560563200, 44438118400, 702660608000, 8725110784000, 129295622144000, 2796896567296000, 57197188186112000, 926039081943040000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..20.

MATHEMATICA

With[{nn=20}, CoefficientList[Series[Exp[ArcTanh[x]+ArcTan[x]], {x, 0, nn}], x]Range[0, nn]!] (* Harvey P. Dale, Jan 12 2013 *)

CROSSREFS

Sequence in context: A051299 A097049 A119490 * A283195 A233294 A287706

Adjacent sequences:  A013171 A013172 A013173 * A013175 A013176 A013177

KEYWORD

nonn

AUTHOR

Patrick Demichel (patrick.demichel(AT)hp.com)

EXTENSIONS

Definition modified by Harvey P. Dale, Jan 12 2013

STATUS

approved

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Last modified May 22 23:18 EDT 2022. Contains 353959 sequences. (Running on oeis4.)