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 A198109 #6 Feb 07 2025 16:44:04
%S A198109 7,6,5,7,2,6,4,4,2,9,2,0,5,4,0,7,1,7,4,8,3,1,0,1,0,4,9,2,3,9,4,4,9,9,
%T A198109 3,8,2,5,9,3,8,8,0,0,4,2,0,4,9,6,3,7,0,7,0,8,5,2,1,5,1,7,2,8,8,4,5,8,
%U A198109 6,9,4,9,7,5,8,1,7,4,9,7,9,4,2,2,8,3,9,2,5,1,1,7,8,8,9,2,8,8,8
%N A198109 Decimal expansion of greatest x having x^2+3x=4*cos(x).
%C A198109 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A198109 least x: -2.072191302711809327379682290027003...
%e A198109 greatest x: 0.7657264429205407174831010492394...
%t A198109 a = 1; b = 3; c = 4;
%t A198109 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A198109 Plot[{f[x], g[x]}, {x, -3, 1}]
%t A198109 r1 = x /. FindRoot[f[x] == g[x], {x, -2.1, -2.9}, WorkingPrecision -> 110]
%t A198109 RealDigits[r1] (* A198108 *)
%t A198109 r2 = x /. FindRoot[f[x] == g[x], {x, .76, .77}, WorkingPrecision -> 110]
%t A198109 RealDigits[r2] (* A198109 *)
%Y A198109 Cf. A197737.
%K A198109 nonn,cons
%O A198109 0,1
%A A198109 _Clark Kimberling_, Oct 21 2011