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 A197843 #8 Feb 07 2025 16:44:04
%S A197843 1,7,7,3,2,3,2,1,5,7,4,9,1,7,1,6,7,2,7,0,3,8,9,9,4,6,4,1,9,7,0,8,1,6,
%T A197843 4,1,4,1,0,2,3,7,2,3,3,5,3,6,6,7,2,8,8,2,4,4,9,4,6,2,8,1,2,1,2,5,3,7,
%U A197843 2,4,5,4,6,6,0,4,1,4,2,7,2,1,9,2,9,7,3,7,5,3,0,9,7,9,2,6,3,7,7,5,8
%N A197843 Decimal expansion of least x having x^2+2x=2*cos(x).
%C A197843 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A197843 least x: -1.77323215749171672703899464197081641...
%e A197843 greatest x: 0.620762336586614714452120247321515...
%t A197843 a = 1; b = 2; c = 2;
%t A197843 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A197843 Plot[{f[x], g[x]}, {x, -2, 1}]
%t A197843 r1 = x /. FindRoot[f[x] == g[x], {x, -1.8, -1.7}, WorkingPrecision -> 110]
%t A197843 RealDigits[r1] (* A197843 *)
%t A197843 r2 = x /. FindRoot[f[x] == g[x], {x, .62, .63}, WorkingPrecision -> 110]
%t A197843 RealDigits[r2] (* A197844 *)
%Y A197843 Cf. A197737.
%K A197843 nonn,cons
%O A197843 1,2
%A A197843 _Clark Kimberling_, Oct 20 2011