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A012663 Expansion of e.g.f.: sech(tanh(x)*exp(x))=1-1/2!*x^2-6/3!*x^3-11/4!*x^4+100/5!*x^5... 0
1, 0, -1, -6, -11, 100, 1043, 2702, -47287, -697656, -2382009, 65150690, 1227815037, 4876299948, -197964434917, -4452683466122, -19212329422319, 1119650941512592, 28926172679801103, 128264089711760074 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

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

MATHEMATICA

With[{nn=20}, CoefficientList[Series[Sech[Tanh[x]Exp[x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Jun 23 2013 *)

CROSSREFS

Sequence in context: A188599 A217934 A012419 * A180929 A212592 A318858

Adjacent sequences:  A012660 A012661 A012662 * A012664 A012665 A012666

KEYWORD

sign

AUTHOR

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

EXTENSIONS

Definition clarified by Harvey P. Dale, Jun 23 2013

STATUS

approved

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Last modified March 2 19:18 EST 2021. Contains 341756 sequences. (Running on oeis4.)