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<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
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