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 A197486 #11 Feb 15 2025 08:30:46
%S A197486 2,8,4,4,3,5,9,8,3,2,2,6,3,6,3,8,8,9,4,4,7,3,6,2,4,6,5,0,1,3,7,5,2,0,
%T A197486 8,7,3,9,6,2,0,1,0,7,2,5,8,7,3,9,3,8,1,8,0,0,3,7,9,5,6,3,1,6,8,4,0,2,
%U A197486 4,5,8,6,8,3,6,8,1,8,0,4,4,4,9,7,0,0,8,2,0,1,2,9,4,1,1,1,8,1,7
%N A197486 Decimal expansion of least x>0 having cos(4x)=(cos(8x))^2.
%C A197486 The Mathematica program includes a graph. See A197476 for a guide for the least x>0 satisfying cos(b*x)=(cos(c*x))^2 for selected b and c.
%H A197486 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%e A197486 0.284435983226363889447362465013752087396201072...
%t A197486 b = 4; c = 8; f[x_] := Cos[x]
%t A197486 t = x /. FindRoot[f[b*x] == f[c*x]^2, {x, .28, .29}, WorkingPrecision -> 100]
%t A197486 RealDigits[t] (* A197486 *)
%t A197486 Plot[{f[b*x], f[c*x]^2}, {x, 0, 0.4}]
%t A197486 RealDigits[ 1/2*ArcTan[ Sqrt[ Root[#^3 - 5#^2 + 19# - 7&, 1]]], 10, 99] // First (* _Jean-François Alcover_, Feb 27 2013 *)
%Y A197486 Cf. A197476.
%K A197486 nonn,cons
%O A197486 0,1
%A A197486 _Clark Kimberling_, Oct 15 2011