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A009838 Expansion of e.g.f.: tanh(x)/(1+x). 1
0, 1, -2, 4, -16, 96, -576, 3760, -30080, 278656, -2786560, 30298368, -363580416, 4748913664, -66484791296, 995368112128, -15925889794048, 270949991841792, -4877099853152256, 92635808324780032, -1852716166495600640 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Unsigned sequence satisfies a(n)=na(n-1)+b(n-1) where b(n) is defined in A009006. E.g.f. tanh(z)/(1-z). - Mario Catalani (mario.catalani(AT)unito.it), Feb 10 2003

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

FORMULA

|a(n)| ~ n! * tanh(1). - Vaclav Kotesovec, Sep 22 2013

MAPLE

G(x):= tanh(x)/(1+x): f[0]:=G(x): for n from 1 to 21 do f[n]:=diff(f[n-1], x) od: x:=0: seq(f[n], n=0..20); # Zerinvary Lajos, Apr 03 2009

MATHEMATICA

With[{nn=20}, CoefficientList[Series[Tanh[x]/(1+x), {x, 0, nn}], x] Range[ 0, nn]!] (* Harvey P. Dale, Jul 18 2013 *)

CROSSREFS

Sequence in context: A026089 A052835 A009565 * A088335 A066318 A066952

Adjacent sequences:  A009835 A009836 A009837 * A009839 A009840 A009841

KEYWORD

sign,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

Prior Mathematica program replaced and definition clarified by Harvey P. Dale, Jul 18 2013

STATUS

approved

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Last modified January 16 21:37 EST 2019. Contains 319206 sequences. (Running on oeis4.)