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 A198217 #6 Feb 07 2025 16:44:05
%S A198217 5,9,4,8,6,3,2,8,0,3,5,7,7,1,8,7,1,4,1,7,1,5,9,2,0,7,7,9,0,1,0,2,7,8,
%T A198217 7,9,8,5,8,9,2,3,1,4,3,6,2,3,3,0,7,1,6,5,9,4,0,1,0,4,6,0,3,6,1,2,2,2,
%U A198217 0,2,3,7,9,1,3,1,2,7,6,0,4,4,5,2,2,4,8,4,5,7,6,4,2,3,6,0,8,3,8
%N A198217 Decimal expansion of greatest x having 3*x^2+x=2*cos(x).
%C A198217 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A198217 least x: -0.850440081427008538547913177891557825...
%e A198217 greatest x: 0.59486328035771871417159207790102787...
%t A198217 a = 3; b = 1; c = 2;
%t A198217 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A198217 Plot[{f[x], g[x]}, {x, -1, 1}]
%t A198217 r1 = x /. FindRoot[f[x] == g[x], {x, -.9, -.8}, WorkingPrecision -> 110]
%t A198217 RealDigits[r1] (* A198216 *)
%t A198217 r2 = x /. FindRoot[f[x] == g[x], {x, .59, .6}, WorkingPrecision -> 110]
%t A198217 RealDigits[r2] (* A198217 *)
%Y A198217 Cf. A197737.
%K A198217 nonn,cons
%O A198217 0,1
%A A198217 _Clark Kimberling_, Oct 22 2011