A012720 - OEIS

A012720

sech(arctanh(x)*exp(x))=1-1/2!*x^2-6/3!*x^3-27/4!*x^4-60/5!*x^5...

1, 0, -1, -6, -27, -60, 435, 8750, 84777, 475272, -2114745, -106313438, -1794336819, -17317361204, 18165128891, 5261034602070, 135408683857873, 2003263412796176, 6167034429608463, -699433926727865526

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OFFSET

0,4

LINKS

Table of n, a(n) for n=0..19.

MATHEMATICA

With[{nn=20}, CoefficientList[Series[Sech[ArcTanh[x]Exp[x]], {x, 0, nn}], x]Range[0, nn]!] (* Harvey P. Dale, Oct 07 2012 *)

CROSSREFS

Sequence in context: A100784 A174974 A273578 * A012365 A217189 A363696

Adjacent sequences: A012717 A012718 A012719 * A012721 A012722 A012723

KEYWORD

sign

AUTHOR

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

STATUS

approved