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 A199452 #8 Feb 08 2025 09:35:27
%S A199452 3,9,4,7,8,4,8,4,4,9,4,1,2,8,5,9,9,7,8,1,5,2,7,3,5,3,6,2,8,9,9,5,7,0,
%T A199452 2,5,5,3,4,7,1,7,2,2,1,1,6,4,9,7,3,5,0,5,2,6,6,8,5,5,6,4,1,3,7,6,8,4,
%U A199452 4,6,5,8,6,5,5,8,9,7,3,3,3,9,0,7,3,6,7,8,6,9,9,1,4,1,7,4,7,8,7
%N A199452 Decimal expansion of x>0 satisfying 3*x^2+3*x*sin(x)=cos(x).
%C A199452 See A199370 for a guide to related sequences. The Mathematica program includes a graph.
%H A199452 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%e A199452 0.3947848449412859978152735362899570255347172211...
%t A199452 a = 3; b = 3; c = 1;
%t A199452 f[x_] := a*x^2 + b*x*Sin[x]; g[x_] := c*Cos[x]
%t A199452 Plot[{f[x], g[x]}, {x, -Pi, Pi}, {AxesOrigin -> {0, 0}}]
%t A199452 r = x /. FindRoot[f[x] == g[x], {x, .39, .40}, WorkingPrecision -> 110]
%t A199452 RealDigits[r] (* A199452 *)
%Y A199452 Cf. A199429.
%K A199452 nonn,cons
%O A199452 0,1
%A A199452 _Clark Kimberling_, Nov 06 2011