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 A198211 #7 Feb 07 2025 16:44:05
%S A198211 5,3,5,4,2,8,2,4,4,1,6,4,6,5,6,9,1,4,1,2,5,9,7,8,6,8,5,3,0,8,3,9,7,3,
%T A198211 8,0,8,7,9,6,8,4,4,3,9,2,2,7,5,1,4,6,3,0,1,8,7,8,4,2,0,9,8,6,7,4,8,3,
%U A198211 8,7,7,8,4,5,6,9,7,8,4,5,0,0,9,7,5,4,8,8,0,9,7,2,8,9,1,9,4,5,7
%N A198211 Decimal expansion of x>0 having 3*x^2=cos(x).
%C A198211 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A198211 x=0.535428244164656914125978685308397380...
%t A198211 a = 3; b = 0; c = 1;
%t A198211 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A198211 Plot[{f[x], g[x]}, {x, -1, 1}]
%t A198211 r = x /. FindRoot[f[x] == g[x], {x, 0.53, 0.54}, WorkingPrecision -> 110]
%t A198211 RealDigits[r] (* A198211 *)
%Y A198211 Cf. A197737.
%K A198211 nonn,cons
%O A198211 0,1
%A A198211 _Clark Kimberling_, Oct 22 2011