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A009126 Expansion of e.g.f. cosh(log(1+tanh(x))). 2
1, 0, 1, -3, 4, 0, 16, -168, 64, 3840, 256, -177408, 1024, 11182080, 4096, -951886848, 16384, 104932638720, 65536, -14544442687488, 262144, 2475749026037760, 1048576, -507711943255523328, 4194304, 123460740095095603200, 16777216 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
LINKS
FORMULA
E.g.f.: (1/Q(0)+Q(0))/2, where Q(k) = 1 - x/( 2*k+1 + x/Q(k+1) ); (continued fraction). - Sergei N. Gladkovskii, Dec 20 2013
MATHEMATICA
With[{nn=30}, CoefficientList[Series[Cosh[Log[1+Tanh[x]]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, May 18 2014 *)
PROG
(PARI) x='x+O('x^30); Vec(serlaplace(cosh(log(1+tanh(x))))) \\ G. C. Greubel, Jul 28 2018
(Magma) m:=30; R<x>:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!(Cosh(Log(1+Tanh(x))))); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, Jul 28 2018
CROSSREFS
Cf. A009570.
Sequence in context: A099447 A078067 A192442 * A322278 A102222 A171657
KEYWORD
sign,easy
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
Previous Mathematica program replaced and definition clarified by Harvey P. Dale, May 18 2014
STATUS
approved

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Last modified May 22 17:27 EDT 2024. Contains 372758 sequences. (Running on oeis4.)