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 A199864 #8 Feb 08 2025 22:37:25
%S A199864 6,6,1,5,7,3,3,0,1,8,2,0,5,9,1,2,1,3,9,3,3,8,6,7,1,1,5,4,1,2,8,3,4,2,
%T A199864 8,3,3,8,0,2,3,4,0,0,5,6,3,2,4,6,9,9,1,4,2,9,2,5,2,0,2,4,2,7,8,3,0,7,
%U A199864 0,8,2,2,9,9,5,2,4,5,0,6,0,1,7,3,6,9,8,0,9,0,4,4,6,2,5,1,2,7,5
%N A199864 Decimal expansion of x>0 satisfying 4*x^2-x*cos(x)=2*sin(x).
%C A199864 See A199597 for a guide to related sequences. The Mathematica program includes a graph.
%H A199864 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%e A199864 0.66157330182059121393386711541283428338023400...
%t A199864 a = 4; b = -1; c = 2;
%t A199864 f[x_] := a*x^2 + b*x*Cos[x]; g[x_] := c*Sin[x]
%t A199864 Plot[{f[x], g[x]}, {x, -2, 2}, {AxesOrigin -> {0, 0}}]
%t A199864 r = x /. FindRoot[f[x] == g[x], {x, .66, .67}, WorkingPrecision -> 110]
%t A199864 RealDigits[r] (* A199864 *)
%Y A199864 Cf. A199597.
%K A199864 nonn,cons
%O A199864 0,1
%A A199864 _Clark Kimberling_, Nov 11 2011