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 A198236 #6 Feb 07 2025 16:44:05
%S A198236 1,3,7,9,3,2,3,3,2,0,9,8,6,8,8,7,6,5,8,6,3,7,2,5,6,1,8,9,5,6,0,1,7,3,
%T A198236 7,8,7,6,6,2,5,8,2,2,2,4,2,6,9,6,0,7,5,0,0,8,7,2,2,6,0,0,6,2,4,6,3,9,
%U A198236 2,1,1,7,7,2,4,9,2,0,8,1,2,3,8,0,4,4,9,4,7,9,7,6,9,8,2,0,2,1,4
%N A198236 Decimal expansion of least x having 3*x^2+4x=cos(x).
%C A198236 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A198236 least x: -1.379323320986887658637256189560173787662...
%e A198236 greatest x: 0.2110472944900402842082192926601908288084...
%t A198236 a = 3; b = 4; c = 1;
%t A198236 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A198236 Plot[{f[x], g[x]}, {x, -2, 1}]
%t A198236 r1 = x /. FindRoot[f[x] == g[x], {x, -1.4, -1.3}, WorkingPrecision -> 110]
%t A198236 RealDigits[r1](* A198236 *)
%t A198236 r2 = x /. FindRoot[f[x] == g[x], {x, .21, .22}, WorkingPrecision -> 110]
%t A198236 RealDigits[r2] (* A198237 *)
%Y A198236 Cf. A197737.
%K A198236 nonn,cons
%O A198236 1,2
%A A198236 _Clark Kimberling_, Oct 23 2011