This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A272429 #6 Feb 16 2025 08:33:34
%S A272429 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 A272429 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 A272429 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 A272429 Asymptotic mean (normalized by n) of the second largest connected component in a random mapping on n symbols.
%D A272429 Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.4.2 Random mapping statistics, p. 290.
%H A272429 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 A272429 Eric Weisstein's MathWorld, <a href="https://mathworld.wolfram.com/Flajolet-OdlyzkoConstant.html">Flajolet-Odlyzko Constant</a>
%F A272429 2*integral_{0..infinity} 1 - e^(Ei(-x)/2)*(1 - Ei(-x)/2) dx, where Ei is the exponential integral.
%e A272429 0.17090961985966239214460728413311738704719072962628832355853881...
%t A272429 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 A272429 Cf. A084945, A143297, A261873.
%K A272429 nonn,cons
%O A272429 0,2
%A A272429 _Jean-François Alcover_, Apr 29 2016