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 A197580 #8 Apr 10 2021 16:56:22
%S A197580 4,9,8,6,3,6,5,1,5,4,7,9,9,9,8,2,8,5,8,3,2,1,9,1,7,2,8,7,7,2,3,2,2,6,
%T A197580 9,7,0,6,6,0,4,5,6,3,7,7,2,4,3,0,2,0,1,9,3,5,7,0,3,3,5,9,9,2,3,6,1,3,
%U A197580 5,3,2,2,5,3,8,6,1,5,4,6,8,5,9,8,7,1,0,5,3,1,9,7,5,0,7,9,2,8,4
%N A197580 Decimal expansion of least x > 0 having cos(Pi*x/2) = cos(2*x)^2.
%C A197580 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 A197580 x=0.498636515479998285832191728772322697066045637...
%t A197580 b = Pi/2; c = 2; f[x_] := Sin[x]
%t A197580 t = x /. FindRoot[f[b*x] == f[c*x]^2, {x, .49, 5}, WorkingPrecision -> 200]
%t A197580 RealDigits[t] (* A197580 *)
%t A197580 Plot[{f[b*x], f[c*x]^2}, {x, 0, 2}]
%Y A197580 Cf. A197133.
%K A197580 nonn,cons
%O A197580 0,1
%A A197580 _Clark Kimberling_, Oct 16 2011