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 A197808 #7 Jan 16 2022 00:49:53
%S A197808 1,2,0,1,5,3,8,2,9,9,3,4,0,5,7,5,1,1,1,4,8,1,5,0,8,1,6,6,5,6,8,8,5,0,
%T A197808 4,9,1,0,6,0,8,3,5,8,1,1,0,1,8,6,0,2,7,0,4,3,2,1,1,2,0,6,0,5,6,8,0,8,
%U A197808 5,8,4,4,0,2,1,6,9,4,5,2,2,5,8,8,4,9,1,3,7,1,2,0,5,2,8,4,3,1,6
%N A197808 Decimal expansion of x>0 having x^2 = 4*cos(x).
%C A197808 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A197808 x = 1.201538299340575111481508166568850491060835...
%t A197808 a = 1; b = 0; c = 4;
%t A197808 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A197808 Plot[{f[x], g[x]}, {x, -1.5, 1.5}]
%t A197808 r1 = x /. FindRoot[f[x] == g[x], {x, 1.2, 1.3}, WorkingPrecision -> 110]
%t A197808 RealDigits[r1] (* A197808 *)
%Y A197808 Cf. A197737.
%K A197808 nonn,cons
%O A197808 1,2
%A A197808 _Clark Kimberling_, Oct 20 2011