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