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 A198102 #6 Feb 07 2025 16:44:04
%S A198102 2,6,6,6,5,0,9,8,2,1,5,2,5,4,2,1,4,7,1,1,9,2,9,0,9,8,8,1,2,4,3,5,6,5,
%T A198102 4,8,2,0,4,0,5,8,9,6,3,2,5,6,0,6,1,3,7,4,7,1,3,8,6,7,6,2,0,9,2,6,7,6,
%U A198102 5,2,5,1,2,9,3,0,3,2,0,1,7,1,2,6,8,5,9,7,1,2,8,2,7,4,4,3,5,9,7
%N A198102 Decimal expansion of least x having x^2+3x=cos(x).
%C A198102 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A198102 least x: -2.666509821525421471192909881243565...
%e A198102 greatest x: 0.2910714507806038010117661064073...
%t A198102 a = 1; b = 3; c = 1;
%t A198102 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A198102 Plot[{f[x], g[x]}, {x, -3, 1}]
%t A198102 r1 = x /. FindRoot[f[x] == g[x], {x, -3, -2}, WorkingPrecision -> 110]
%t A198102 RealDigits[r1] (* A198102 *)
%t A198102 r2 = x /. FindRoot[f[x] == g[x], {x, .29, .3}, WorkingPrecision -> 110]
%t A198102 RealDigits[r2] (* A198103 *)
%Y A198102 Cf. A197737.
%K A198102 nonn,cons
%O A198102 1,1
%A A198102 _Clark Kimberling_, Oct 21 2011