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 A198238 #6 Feb 07 2025 16:44:05
%S A198238 1,4,0,9,3,6,3,9,2,1,6,3,5,7,7,7,8,4,4,7,7,2,8,6,9,3,6,8,8,0,1,5,3,9,
%T A198238 7,9,5,1,1,7,7,3,5,0,3,8,5,9,2,6,5,8,5,5,0,3,9,0,2,5,4,6,5,2,1,7,9,0,
%U A198238 0,3,7,0,4,7,8,5,6,4,0,7,7,3,9,9,1,4,4,8,5,5,7,3,0,5,7,4,4,2,9
%N A198238 Decimal expansion of least x having 3*x^2+4x=2*cos(x).
%C A198238 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A198238 least x: -1.40936392163577784477286936880153979511...
%e A198238 greatest x: 0.36624081566046371838415818869764440...
%t A198238 a = 3; b = 4; c = 2;
%t A198238 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A198238 Plot[{f[x], g[x]}, {x, -2, 1}]
%t A198238 r1 = x /. FindRoot[f[x] == g[x], {x, -1.5, -1.4}, WorkingPrecision -> 110]
%t A198238 RealDigits[r1](* A198238 *)
%t A198238 r2 = x /. FindRoot[f[x] == g[x], {x, .36, .37}, WorkingPrecision -> 110]
%t A198238 RealDigits[r2](* A198239 *)
%Y A198238 Cf. A197737.
%K A198238 nonn,cons
%O A198238 1,2
%A A198238 _Clark Kimberling_, Oct 23 2011