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 A271871 #14 Apr 20 2016 10:34:40
%S A271871 4,8,3,4,9,8,3,4,7,1,5,4,4,2,5,5,0,0,9,2,4,0,2,6,3,6,0,8,5,0,7,5,6,1,
%T A271871 9,4,4,4,9,2,4,6,6,7,9,5,4,1,3,3,8,1,0,4,3,2,9,2,6,4,9,4,1,5,5,2,4,7,
%U A271871 0,9,3,3,5,1,1,4,0,3,2,9,5,9,9,2,3,7,3,2,3,1,9,6,0,8,7,7,0,1,8,9,4,8,8
%N A271871 Decimal expansion of a constant related to the expected number of vertices of the largest tree associated with a random mapping on n symbols.
%D A271871 Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.4.2 Random Mapping Statistics, p. 289.
%H A271871 Xavier Gourdon, <a href="http://dx.doi.org/10.1016/S0012-365X(97)00115-5">Largest component in random combinatorial structures</a>, Discrete Mathematics 180, 1998, Pages 185-209.
%e A271871 0.48349834715442550092402636085075619444924667954133810432926494155247...
%t A271871 digits = 98; F[x_] := 1 - Exp[-x]/Sqrt[Pi*x] - Erf[Sqrt[x]]; Clear[f]; f[m_] := f[m] = 2 NIntegrate[1-(1-F[x])^-1, {x, 0, m}, WorkingPrecision -> digits+10]; f[m = 100]; f[m = 2 m]; Print["m = ", m]; While[ RealDigits[ f[m], 10, digits + 5][[1]] != RealDigits[f[m/2], 10, digits + 5][[1]], m = 2 m; Print["m = ", m]]; RealDigits[f[m/2], 10, digits + 5][[1]]
%Y A271871 Cf. A084945, A143297, A244067, A244258, A244261, A261873.
%K A271871 nonn,cons
%O A271871 0,1
%A A271871 _Jean-François Alcover_, Apr 20 2016