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 A198213 #6 Feb 07 2025 16:44:05
%S A198213 9,0,6,5,9,2,4,7,4,0,9,2,4,3,7,9,6,6,9,7,9,3,0,6,8,2,4,6,7,2,1,4,9,3,
%T A198213 8,0,6,0,4,9,7,0,7,3,7,7,5,2,2,3,6,1,4,9,7,3,2,4,7,2,0,4,1,9,2,1,2,1,
%U A198213 6,4,9,5,8,2,5,2,1,8,0,7,1,5,3,3,3,1,3,1,1,3,6,8,2,3,7,4,6,8,2
%N A198213 Decimal expansion of x>0 having 3*x^2=4*cos(x).
%C A198213 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A198213 x=0.90659247409243796697930682467214938...
%t A198213 a = 3; b = 0; c = 4;
%t A198213 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A198213 Plot[{f[x], g[x]}, {x, -1, 1}]
%t A198213 r = x /. FindRoot[f[x] == g[x], {x, 0.90, 0.91}, WorkingPrecision -> 110]
%t A198213 RealDigits[r] (* A198213 *)
%Y A198213 Cf. A197737.
%K A198213 nonn,cons
%O A198213 0,1
%A A198213 _Clark Kimberling_, Oct 22 2011