cp's OEIS Frontend

A199280 Decimal expansion of x>0 satisfying 3*x^2+x*cos(x)=1.

%I A199280 #8 Feb 07 2025 16:44:05
%S A199280 4,4,6,2,5,9,8,1,1,7,7,1,7,6,5,9,5,6,2,9,6,1,7,0,1,2,1,1,9,9,0,9,2,3,
%T A199280 2,6,4,4,6,9,3,5,0,9,1,3,3,4,1,2,7,9,6,9,8,5,4,2,0,8,6,8,5,2,6,6,8,9,
%U A199280 8,0,6,4,5,2,4,2,4,1,6,3,6,5,8,4,1,9,3,0,5,1,1,2,4,0,2,6,1,6,4
%N A199280 Decimal expansion of x>0 satisfying 3*x^2+x*cos(x)=1.
%C A199280 See A199170 for a guide to related sequences. The Mathematica program includes a graph.
%H A199280 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%e A199280 negative: -0.7165503839061782023923880301835513...
%e A199280 positive:  0.4462598117717659562961701211990923...
%t A199280 Remove["Global`*"];
%t A199280 a = 3; b = 1; c = 1;
%t A199280 f[x_] := a*x^2 + b*x*Cos[x]; g[x_] := c
%t A199280 Plot[{f[x], g[x]}, {x, -1, 1}, {AxesOrigin -> {0, 0}}]
%t A199280 r = x /. FindRoot[f[x] == g[x], {x, -.8, -.7}, WorkingPrecision -> 110]
%t A199280 RealDigits[r]    (* A199279 *)
%t A199280 r = x /. FindRoot[f[x] == g[x], {x, .44, .45}, WorkingPrecision -> 110]
%t A199280 RealDigits[r]    (* A199280 *)
%Y A199280 Cf. A199170.
%K A199280 nonn,cons
%O A199280 0,1
%A A199280 _Clark Kimberling_, Nov 04 2011