%I #14 May 14 2019 23:38:43
%S 3,5,1,7,3,3,7,1,1,2,4,9,1,9,5,8,2,6,0,2,4,9,0,9,3,0,0,9,2,9,9,5,1,0,
%T 6,5,1,7,1,4,6,4,2,1,5,5,1,7,1,1,1,8,0,4,0,4,6,6,4,3,8,4,6,1,0,9,9,6,
%U 0,6,1,0,7,2,0,3,3,8,7,1,0,8,9,6,8,3,2,3,0,3,8,3,2,1,9,1,5,6,9
%N Decimal expansion of the number x satisfying 2x=exp(-x).
%C See A202322 for a guide to related sequences. The Mathematica program includes a graph.
%H G. C. Greubel, <a href="/A202356/b202356.txt">Table of n, a(n) for n = 0..5000</a>
%H <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>
%e x=0.35173371124919582602490930092995106517146...
%t u = 2; v = 0;
%t f[x_] := u*x + v; g[x_] := E^-x
%t Plot[{f[x], g[x]}, {x, 0, 2}, {AxesOrigin -> {0, 0}}]
%t r = x /. FindRoot[f[x] == g[x], {x, .35, .36}, WorkingPrecision -> 110]
%t RealDigits[r] (* A202356 *)
%t RealDigits[ ProductLog[1/2], 10, 99] // First (* _Jean-François Alcover_, Feb 14 2013 *)
%o (PARI) lambertw(1/2) \\ _G. C. Greubel_, Jun 10 2017
%Y Cf. A202322.
%K nonn,cons
%O 0,1
%A _Clark Kimberling_, Dec 18 2011