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 A198351 #6 Feb 07 2025 16:44:05
%S A198351 7,4,4,2,1,9,8,9,8,5,2,7,0,6,2,4,6,8,7,3,2,7,5,8,2,8,0,0,6,3,7,0,2,8,
%T A198351 8,5,9,7,2,5,6,8,0,7,4,5,1,0,0,1,7,4,3,0,9,4,0,6,3,6,4,2,7,1,1,7,1,2,
%U A198351 5,8,7,0,8,7,3,8,6,9,7,0,1,5,4,8,7,0,1,4,2,1,8,2,7,1,8,3,6,2,1
%N A198351 Decimal expansion of least x having 4*x^2+x=2*cos(x).
%C A198351 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A198351 least x: -0.74421989852706246873275828006370...
%e A198351 greatest x: 0.541418903172906711296921967206240...
%t A198351 a = 4; b = 1; c = 2;
%t A198351 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A198351 Plot[{f[x], g[x]}, {x, -1, 1}]
%t A198351 r1 = x /. FindRoot[f[x] == g[x], {x, -.8, -.7}, WorkingPrecision -> 110]
%t A198351 RealDigits[r1] (* A198351 *)
%t A198351 r2 = x /. FindRoot[f[x] == g[x], {x, .5, .6}, WorkingPrecision -> 110]
%t A198351 RealDigits[r2] (* A198352 *)
%Y A198351 Cf. A197737.
%K A198351 nonn,cons
%O A198351 0,1
%A A198351 _Clark Kimberling_, Oct 23 2011