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 A199599 #8 Feb 08 2025 13:27:11
%S A199599 2,1,2,5,9,8,6,5,4,9,9,7,7,7,0,3,0,4,2,5,1,2,1,6,2,5,5,7,8,8,0,4,3,1,
%T A199599 8,4,7,2,1,0,0,7,9,4,1,4,4,8,1,7,8,7,8,7,7,6,3,0,8,5,5,5,2,6,5,9,0,7,
%U A199599 3,8,7,4,2,9,2,8,5,4,4,8,2,8,5,5,0,2,4,6,7,5,6,2,4,7,5,7,8,3,8
%N A199599 Decimal expansion of x>0 satisfying x^2+x*cos(x)=4*sin(x).
%C A199599 See A199597 for a guide to related sequences. The Mathematica program includes a graph.
%H A199599 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%e A199599 2.1259865499777030425121625578804318472100...
%t A199599 a = 1; b = 1; c = 4;
%t A199599 f[x_] := a*x^2 + b*x*Cos[x]; g[x_] := c*Sin[x]
%t A199599 Plot[{f[x], g[x]}, {x, -Pi, Pi}, {AxesOrigin -> {0, 0}}]
%t A199599 r = x /. FindRoot[f[x] == g[x], {x, 2.12, 2.13}, WorkingPrecision -> 110]
%t A199599 RealDigits[r] (* A199599 *)
%Y A199599 Cf. A199597.
%K A199599 nonn,cons
%O A199599 1,1
%A A199599 _Clark Kimberling_, Nov 08 2011