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 A197491 #11 Feb 16 2025 05:25:06
%S A197491 5,7,8,5,4,8,9,2,5,4,2,5,7,1,8,3,8,3,2,0,4,0,7,3,6,7,3,2,4,8,8,0,2,1,
%T A197491 1,8,2,8,6,8,1,7,0,1,7,9,2,0,6,9,1,2,1,4,6,3,7,8,2,7,3,3,1,7,8,5,0,1,
%U A197491 2,8,6,9,6,2,4,5,6,6,9,4,3,2,0,2,7,2,4,1,7,9,2,6,8,1,8,2,6,9,0
%N A197491 Decimal expansion of least x > 0 having cos(x) = cos(3*Pi*x/2)^2.
%C A197491 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.
%C A197491 This number is irrational. I cannot prove it to be algebraic or transcendental. - _Charles R Greathouse IV_, Feb 16 2025
%e A197491 0.57854892542571838320407367324880211828681701...
%t A197491 b = 1; c = 3 Pi/2; f[x_] := Cos[x]
%t A197491 t = x /. FindRoot[f[b*x] == f[c*x]^2, {x, .56, .58}, WorkingPrecision -> 110]
%t A197491 RealDigits[t] (* A197491 *)
%t A197491 Plot[{f[b*x], f[c*x]^2}, {x, 0, Pi/3}]
%Y A197491 Cf. A197476.
%K A197491 nonn,cons
%O A197491 0,1
%A A197491 _Clark Kimberling_, Oct 15 2011