A012727 exp(arctanh(x)*arctan(x))=1+2/2!*x^2+12/4!*x^4+328/6!*x^6+13328/8!*x^8...

1, 2, 12, 328, 13328, 1160352, 123701952, 22207125120, 4532782825728, 1380071532433920, 459909185638812672, 212375023941305272320, 104929881035116227072000, 68350141067274779587092480

Offset

0,2

Links

Table of n, a(n) for n=0..13.

Mathematica

With[{nn=30}, Take[CoefficientList[Series[Exp[ArcTanh[x]*ArcTan[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Ray Chandler, Nov 28 2016 *)

Crossrefs

Sequence in context: A300045 A091472 A156518 * A296622 A325756 A181142

Adjacent sequences: A012724 A012725 A012726 * A012728 A012729 A012730

Keyword

nonn

Author

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

Status

approved