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 A198135 #11 Apr 10 2025 06:51:22
%S A198135 6,9,7,5,3,4,5,5,5,2,2,8,4,1,2,9,9,3,7,9,5,1,7,4,0,6,6,2,5,2,1,2,9,8,
%T A198135 8,7,4,6,5,4,7,9,0,3,6,1,1,5,3,4,4,7,5,7,6,5,0,6,4,9,3,5,8,6,6,2,0,1,
%U A198135 5,2,5,6,1,6,3,4,3,2,5,0,2,2,8,7,2,3,3,1,4,5,0,3,7,7,5,7,0,0,6
%N A198135 Decimal expansion of greatest x having 2*x^2+3x=4*cos(x).
%C A198135 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A198135 Least x: -1.5399952272668390818059885802040...
%e A198135 Greatest x: 0.6975345552284129937951740662521298...
%t A198135 a = 2; b = 3; c = 4;
%t A198135 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A198135 Plot[{f[x], g[x]}, {x, -2, 1}]
%t A198135 r1 = x /. FindRoot[f[x] == g[x], {x, -1.54, -1.539}, WorkingPrecision -> 110]
%t A198135 RealDigits[r1] (* A198134 *)
%t A198135 r2 = x /. FindRoot[f[x] == g[x], {x, .79, .70}, WorkingPrecision -> 110]
%t A198135 RealDigits[r2] (* A198135 *)
%Y A198135 Cf. A197737.
%K A198135 nonn,cons
%O A198135 0,1
%A A198135 _Clark Kimberling_, Oct 22 2011