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 A198101 #6 Feb 07 2025 16:44:04
%S A198101 4,2,2,2,7,4,9,5,2,8,7,9,4,9,2,7,3,2,4,4,8,4,2,4,9,6,7,6,6,1,0,8,2,0,
%T A198101 1,2,8,1,6,3,3,7,1,2,5,9,8,2,1,1,0,6,8,4,2,5,6,3,8,6,4,9,8,5,9,8,2,7,
%U A198101 0,2,6,1,8,7,8,2,0,1,6,6,2,4,8,1,4,0,6,0,0,0,9,9,4,5,8,4,0,4,0
%N A198101 Decimal expansion of greatest x having x^2-4x=-2*cos(x).
%C A198101 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A198101 least x: 0.50130475545480646339369035756819...
%e A198101 greatest x: 4.222749528794927324484249676610...
%t A198101 a = 1; b = -4; c = -2;
%t A198101 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A198101 Plot[{f[x], g[x]}, {x, 0, 5}]
%t A198101 r1 = x /. FindRoot[f[x] == g[x], {x, .5, .51}, WorkingPrecision -> 110]
%t A198101 RealDigits[r1] (* A198100 *)
%t A198101 r2 = x /. FindRoot[f[x] == g[x], {x, 4.2, 4.3}, WorkingPrecision -> 110]
%t A198101 RealDigits[r2] (* A198101 *)
%Y A198101 Cf. A197737.
%K A198101 nonn,cons
%O A198101 1,1
%A A198101 _Clark Kimberling_, Oct 21 2011