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 A199661 #9 Feb 08 2025 13:24:08
%S A199661 5,8,1,1,4,8,2,2,7,2,0,3,4,1,2,1,1,1,9,8,6,7,9,7,6,7,4,6,2,0,6,4,9,6,
%T A199661 4,4,1,8,5,6,1,6,2,0,1,6,1,1,7,0,7,3,7,6,2,0,1,5,4,7,9,9,6,6,0,2,2,5,
%U A199661 9,3,2,1,8,0,0,7,7,5,4,2,9,9,7,1,8,6,2,4,3,7,4,6,6,1,7,1,7,6,0
%N A199661 Decimal expansion of x>0 satisfying 2*x^2+2*x*cos(x)=3*sin(x).
%C A199661 See A199597 for a guide to related sequences. The Mathematica program includes a graph.
%H A199661 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%e A199661 0.5811482272034121119867976746206496441856...
%t A199661 a = 2; b = 2; c = 3;
%t A199661 f[x_] := a*x^2 + b*x*Cos[x]; g[x_] := c*Sin[x]
%t A199661 Plot[{f[x], g[x]}, {x, -1, 1}, {AxesOrigin -> {0, 0}}]
%t A199661 r = x /. FindRoot[f[x] == g[x], {x, .58, .59}, WorkingPrecision -> 110]
%t A199661 RealDigits[r] (* A199661 *)
%Y A199661 Cf. A199597.
%K A199661 nonn,cons
%O A199661 0,1
%A A199661 _Clark Kimberling_, Nov 09 2011