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 A197480 #10 Feb 14 2025 17:38:54
%S A197480 5,6,8,8,7,1,9,6,6,4,5,2,7,2,7,7,7,8,8,9,4,7,2,4,9,3,0,0,2,7,5,0,4,1,
%T A197480 7,4,7,9,2,4,0,2,1,4,5,1,7,4,7,8,7,6,3,6,0,0,7,5,9,1,2,6,3,3,6,8,0,4,
%U A197480 9,1,7,3,6,7,3,6,3,6,0,8,8,9,9,4,0,1,6,4,0,2,5,8,8,2,2,3,6,3,5
%N A197480 Decimal expansion of least x>0 having cos(2x)=(cos 4x)^2.
%C A197480 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 A197480 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%e A197480 0.5688719664527277788947249300275041747924021...
%t A197480 b = 2; c = 4; f[x_] := Cos[x]
%t A197480 t = x /. FindRoot[f[b*x] == f[c*x]^2, {x, .55, .57}, WorkingPrecision -> 200]
%t A197480 RealDigits[t] (* A197480 *)
%t A197480 Plot[{f[b*x], f[c*x]^2}, {x, 0, Pi/4}]
%t A197480 RealDigits[ ArcCos[ Root[ -2 + 4#^2 - 4#^4 + #^6 & , 2]/2], 10, 99] // First (* _Jean-François Alcover_, Feb 19 2013 *)
%Y A197480 Cf. A197476.
%K A197480 nonn,cons
%O A197480 0,1
%A A197480 _Clark Kimberling_, Oct 15 2011