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 A199721 #8 Feb 08 2025 22:27:04
%S A199721 1,4,6,4,3,3,5,1,0,3,8,6,8,0,6,7,6,6,9,6,2,3,7,2,0,4,7,8,4,2,0,4,0,8,
%T A199721 3,7,6,2,4,9,2,5,7,4,8,6,5,8,7,2,1,7,0,0,0,4,2,3,4,7,0,1,5,6,4,2,9,2,
%U A199721 1,9,5,7,5,8,3,4,2,4,6,0,5,7,9,4,7,6,4,9,5,8,0,7,8,8,8,3,2,1,0
%N A199721 Decimal expansion of x>0 satisfying x^2-x*cos(x)=2*sin(x).
%C A199721 See A199597 for a guide to related sequences. The Mathematica program includes a graph.
%H A199721 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%e A199721 1.46433510386806766962372047842040837624925...
%t A199721 a = 1; b = -1; c = 2;
%t A199721 f[x_] := a*x^2 + b*x*Cos[x]; g[x_] := c*Sin[x]
%t A199721 Plot[{f[x], g[x]}, {x, -Pi, Pi}, {AxesOrigin -> {0, 0}}]
%t A199721 r = x /. FindRoot[f[x] == g[x], {x, 1.4, 1.5}, WorkingPrecision -> 110]
%t A199721 RealDigits[r] (* A199721 *)
%Y A199721 Cf. A199597.
%K A199721 nonn,cons
%O A199721 1,2
%A A199721 _Clark Kimberling_, Nov 09 2011