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 A199449 #8 Feb 08 2025 09:19:55
%S A199449 4,2,9,0,7,9,1,0,6,0,8,7,8,3,9,2,4,1,1,8,7,9,9,4,9,9,5,0,7,0,2,2,0,1,
%T A199449 7,4,7,0,2,3,1,8,6,4,2,1,7,4,4,6,4,3,2,1,6,4,7,4,8,7,5,3,4,6,1,9,6,5,
%U A199449 0,4,0,8,3,3,2,8,4,8,9,7,7,1,7,7,9,3,6,3,6,5,5,8,9,1,2,9,6,5,3
%N A199449 Decimal expansion of x>0 satisfying 3*x^2+2*x*sin(x)=cos(x).
%C A199449 See A199370 for a guide to related sequences. The Mathematica program includes a graph.
%H A199449 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%e A199449 0.429079106087839241187994995070220174702318642...
%t A199449 a = 3; b = 2; c = 1;
%t A199449 f[x_] := a*x^2 + b*x*Sin[x]; g[x_] := c*Cos[x]
%t A199449 Plot[{f[x], g[x]}, {x, -Pi, Pi}, {AxesOrigin -> {0, 0}}]
%t A199449 r = x /. FindRoot[f[x] == g[x], {x, .42, .43}, WorkingPrecision -> 110]
%t A199449 RealDigits[r] (* A199449 *)
%Y A199449 Cf. A199429.
%K A199449 nonn,cons
%O A199449 0,1
%A A199449 _Clark Kimberling_, Nov 06 2011