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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 G. C. Greubel, Table of n, a(n) for n = 0..250 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:=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 Adjacent sequences: A009123 A009124 A009125 * A009127 A009128 A009129 KEYWORD sign,easy AUTHOR R. H. Hardin 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.)