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 A199188 #10 Feb 07 2025 16:44:05
%S A199188 8,8,3,3,3,0,1,9,7,1,9,5,8,9,1,9,3,8,9,2,5,8,9,6,4,5,0,8,8,5,6,7,7,1,
%T A199188 0,7,2,3,5,0,5,9,0,0,8,8,4,2,3,1,8,8,2,3,1,6,6,7,6,3,6,6,7,3,1,6,3,4,
%U A199188 3,1,9,5,8,7,3,3,2,2,6,1,2,9,9,8,7,3,3,1,6,8,8,3,1,9,8,3,3,3,1
%N A199188 Decimal expansion of x < 0 satisfying 2*x^2+x*cos(x) = 1.
%C A199188 See A199170 for a guide to related sequences. The Mathematica program includes a graph.
%H A199188 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%e A199188 negative: -0.883330197195891938925896450885677107...
%e A199188 positive: 0.522945946113111737247623836359811237...
%t A199188 a = 2; b = 1; c = 1;
%t A199188 f[x_] := a*x^2 + b*x*Cos[x]; g[x_] := c
%t A199188 Plot[{f[x], g[x]}, {x, -2, 2}, {AxesOrigin -> {0, 0}}]
%t A199188 r = x /. FindRoot[f[x] == g[x], {x, -.84, -.83}, WorkingPrecision -> 110]
%t A199188 RealDigits[r] (* A199188 *)
%t A199188 r = x /. FindRoot[f[x] == g[x], {x, .52, .53}, WorkingPrecision -> 110]
%t A199188 RealDigits[r] (* A199189 *)
%Y A199188 Cf. A199170.
%K A199188 nonn,cons
%O A199188 0,1
%A A199188 _Clark Kimberling_, Nov 04 2011
%E A199188 Offset corrected by _Georg Fischer_, Aug 02 2021