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 A197517 #7 Feb 16 2025 05:30:32
%S A197517 1,6,5,1,9,5,8,3,1,3,6,2,2,5,0,0,7,8,9,7,6,4,6,7,8,2,8,5,7,3,4,4,4,7,
%T A197517 2,0,3,8,1,2,6,5,5,8,3,9,5,5,9,0,7,8,4,0,3,0,1,0,6,8,1,8,8,8,7,1,2,5,
%U A197517 4,2,3,1,3,9,5,6,6,8,9,4,5,8,7,7,0,0,5,2,4,1,4,1,2,3,4,4,1,1,1
%N A197517 Decimal expansion of least x>0 having cos(Pi*x)=(cos x/2)^2.
%C A197517 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 A197517 This number is irrational. I cannot prove it to be algebraic or transcendental. - _Charles R Greathouse IV_, Feb 16 2025
%e A197517 1.6519583136225007897646782857344472038126558395...
%t A197517 b = Pi; c = 1/2; f[x_] := Cos[x]
%t A197517 t = x /. FindRoot[f[b*x] == f[c*x]^2, {x, 1.65, 1.66},
%t A197517 WorkingPrecision -> 200]
%t A197517 RealDigits[t] (* A197517 *)
%t A197517 Plot[{f[b*x], f[c*x]^2}, {x, 0, 3}]
%Y A197517 Cf. A197476.
%K A197517 nonn,cons
%O A197517 1,2
%A A197517 _Clark Kimberling_, Oct 16 2011