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%I #5 Apr 29 2016 10:45:08
%S 1,7,0,9,0,9,6,1,9,8,5,9,6,6,2,3,9,2,1,4,4,6,0,7,2,8,4,1,3,3,1,1,7,3,
%T 8,7,0,4,7,1,9,0,7,2,9,6,2,6,2,8,8,3,2,3,5,5,8,5,3,8,8,1,0,0,6,3,9,8,
%U 3,6,9,5,3,0,1,5,3,7,3,9,8,9,6,4,8,2,6,6,5,3,7,5,5,3,5
%N Asymptotic mean (normalized by n) of the second largest connected component in a random mapping on n symbols.
%D Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.4.2 Random mapping statistics, p. 290.
%H Xavier Gourdon, <a href="http://algo.inria.fr/gourdon/thesis.html">Combinatoire, Algorithmique et Géométrie des Polynomes</a> Ecole Polytechnique, Paris 1996, page 152 (in French)
%H Eric Weisstein's MathWorld, <a href="http://mathworld.wolfram.com/Flajolet-OdlyzkoConstant.html">Flajolet-Odlyzko Constant</a>
%F 2*integral_{0..infinity} 1 - e^(Ei(-x)/2)*(1 - Ei(-x)/2) dx, where Ei is the exponential integral.
%e 0.17090961985966239214460728413311738704719072962628832355853881...
%t digits = 95; Ei = ExpIntegralEi; 2*NIntegrate[1 - E^(Ei[-x]/2)*(1 - Ei[-x]/2), {x, 0, 200}, WorkingPrecision -> digits + 5] // RealDigits[#, 10, digits]& // First
%Y Cf. A084945, A143297, A261873.
%K nonn,cons
%O 0,2
%A _Jean-François Alcover_, Apr 29 2016
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