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 A198117 #6 Feb 07 2025 16:44:04
%S A198117 8,0,1,5,9,1,9,8,7,2,9,9,7,4,7,2,0,4,3,5,7,7,6,4,4,4,3,2,0,0,0,5,7,7,
%T A198117 9,2,6,0,7,9,0,4,5,1,5,8,6,0,5,8,2,6,0,3,1,9,3,6,5,5,7,5,1,7,4,0,1,5,
%U A198117 8,7,6,7,9,2,2,1,9,6,4,0,0,5,4,4,9,0,8,0,2,4,9,2,2,3,6,0,8,5,2
%N A198117 Decimal expansion of greatest x having 2*x^2+x=3*cos(x).
%C A198117 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A198117 least x: -1.1066958928635031236059456759208208...
%e A198117 greatest x: 0.80159198729974720435776444320005779...
%t A198117 a = 2; b = 1; c = 3;
%t A198117 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A198117 Plot[{f[x], g[x]}, {x, -2, 1}]
%t A198117 r1 = x /. FindRoot[f[x] == g[x], {x, -1.2, -1.1}, WorkingPrecision -> 110]
%t A198117 RealDigits[r1] (* A198116 *)
%t A198117 r2 = x /. FindRoot[f[x] == g[x], {x, .8, .9}, WorkingPrecision -> 110]
%t A198117 RealDigits[r2](* A198117 *)
%Y A198117 Cf. A197737.
%K A198117 nonn,cons
%O A198117 0,1
%A A198117 _Clark Kimberling_, Oct 21 2011