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A009838
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Expansion of e.g.f.: tanh(x)/(1+x).
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1
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0, 1, -2, 4, -16, 96, -576, 3760, -30080, 278656, -2786560, 30298368, -363580416, 4748913664, -66484791296, 995368112128, -15925889794048, 270949991841792, -4877099853152256, 92635808324780032, -1852716166495600640
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OFFSET
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0,3
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COMMENTS
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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
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LINKS
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FORMULA
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MAPLE
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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
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MATHEMATICA
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With[{nn=20}, CoefficientList[Series[Tanh[x]/(1+x), {x, 0, nn}], x] Range[ 0, nn]!] (* Harvey P. Dale, Jul 18 2013 *)
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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EXTENSIONS
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Prior Mathematica program replaced and definition clarified by Harvey P. Dale, Jul 18 2013
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STATUS
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approved
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