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 A198370 #6 Feb 07 2025 16:44:05
%S A198370 2,0,3,4,5,1,3,2,5,5,3,1,9,2,5,0,4,1,5,5,5,1,1,6,8,0,5,0,6,0,6,1,1,9,
%T A198370 9,5,6,1,1,6,1,8,6,7,7,8,9,0,3,4,4,6,3,3,3,3,1,5,2,7,0,3,1,3,9,3,5,5,
%U A198370 9,1,7,6,0,6,0,1,6,8,6,0,1,3,4,9,1,7,1,6,3,2,3,1,6,6,3,3,7,7,6
%N A198370 Decimal expansion of greatest x having 4*x^2+4x=cos(x).
%C A198370 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A198370 least x: -1.1023847462794395958058183658678813...
%e A198370 greatest x: 0.203451325531925041555116805060611...
%t A198370 a = 4; b = 4; c = 1;
%t A198370 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A198370 Plot[{f[x], g[x]}, {x, -2, 1}]
%t A198370 r1 = x /. FindRoot[f[x] == g[x], {x, -1.2, -1.1}, WorkingPrecision -> 110]
%t A198370 RealDigits[r1] (* A198369 *)
%t A198370 r2 = x /. FindRoot[f[x] == g[x], {x, .20, .21}, WorkingPrecision -> 110]
%t A198370 RealDigits[r2] (* A198370 *)
%Y A198370 Cf. A197737.
%K A198370 nonn,cons
%O A198370 0,1
%A A198370 _Clark Kimberling_, Oct 24 2011