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 A198355 #10 Feb 07 2025 16:44:05
%S A198355 9,1,5,5,5,4,3,2,6,5,7,3,5,8,7,0,5,2,9,2,7,0,6,9,6,6,7,5,0,1,3,6,9,5,
%T A198355 1,4,0,5,6,0,6,2,7,2,8,6,0,1,9,5,8,2,7,6,6,0,8,8,9,5,7,8,5,8,4,2,0,8,
%U A198355 5,0,2,7,0,4,3,9,7,6,3,7,5,1,6,6,9,9,2,3,9,5,2,2,5,5,0,5,5,1,5,5,8
%N A198355 Decimal expansion of least x having 4*x^2+x = 4*cos(x).
%C A198355 See A197737 for a guide to related sequences. The Mathematica program includes a graph.
%e A198355 least x: -0.91555432657358705292706966750136951...
%e A198355 greatest x: 0.7424374889656033785172455301643263...
%t A198355 a = 4; b = 1; c = 4;
%t A198355 f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
%t A198355 Plot[{f[x], g[x]}, {x, -1, 1}]
%t A198355 r1 = x /. FindRoot[f[x] == g[x], {x, -1, -.9}, WorkingPrecision -> 110]
%t A198355 RealDigits[r1] (* A198355 *)
%t A198355 r2 = x /. FindRoot[f[x] == g[x], {x, .74, .75}, WorkingPrecision -> 110]
%t A198355 RealDigits[r2] (* A198356 *)
%Y A198355 Cf. A197737.
%K A198355 nonn,cons
%O A198355 0,1
%A A198355 _Clark Kimberling_, Oct 24 2011