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 A197848 #6 Feb 07 2025 16:44:04
%S A197848 8,8,2,0,7,4,3,6,6,1,1,8,4,7,4,9,8,0,2,1,9,8,7,3,9,5,5,2,2,3,9,4,3,7,
%T A197848 4,9,1,5,7,0,7,7,8,0,8,0,9,9,9,0,8,6,6,5,3,2,6,4,6,6,2,7,7,5,0,1,2,1,
%U A197848 6,7,1,9,8,9,9,7,5,8,7,6,4,4,5,0,6,3,7,1,5,5,9,1,3,1,5,9,6,6,0
%N A197848 Decimal expansion of greatest x having x^2+2x=4*cos(x).
%C A197848 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A197848 least x: -1.6989977519984890831842928796985548...
%e A197848 greatest x: 0.88207436611847498021987395522394374915...
%t A197848 a = 1; b = 2; c = 4;
%t A197848 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A197848 Plot[{f[x], g[x]}, {x, -2, 1}]
%t A197848 r1 = x /. FindRoot[f[x] == g[x], {x, -1.7, -1.6}, WorkingPrecision -> 110]
%t A197848 RealDigits[r1] (* A197847 *)
%t A197848 r2 = x /. FindRoot[f[x] == g[x], {x, .88, .89}, WorkingPrecision -> 110]
%t A197848 RealDigits[r2] (* A197848 *)
%Y A197848 Cf. A197737.
%K A197848 nonn,cons
%O A197848 0,1
%A A197848 _Clark Kimberling_, Oct 20 2011