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 A197581 #9 Apr 10 2021 15:33:56
%S A197581 1,6,4,0,6,8,6,1,4,7,6,5,5,5,2,4,9,4,9,7,1,2,3,9,9,1,7,7,4,1,9,8,0,9,
%T A197581 6,1,0,1,1,3,1,0,3,3,1,4,6,9,3,1,1,3,3,9,1,3,1,9,2,8,5,3,4,6,2,8,2,3,
%U A197581 4,2,1,9,2,9,5,5,2,7,5,2,7,1,5,6,0,8,2,5,3,5,0,2,8,7,9,1,0,2,1
%N A197581 Decimal expansion of least x > 0 having cos(Pi*x/2) = cos(x/2)^2.
%C A197581 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.
%e A197581 x=1.640686147655524949712399177419809610113...
%t A197581 b = Pi/2; c = 1/2; f[x_] := Sin[x]
%t A197581 t = x /. FindRoot[f[b*x] == f[c*x]^2, {x, 1.64, 1.641},
%t A197581 WorkingPrecision -> 200]
%t A197581 RealDigits[t] (* A197581 *)
%t A197581 Plot[{f[b*x], f[c*x]^2}, {x, 0, 2}]
%Y A197581 Cf. A197133.
%K A197581 nonn,cons
%O A197581 1,2
%A A197581 _Clark Kimberling_, Oct 16 2011