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 A197519 #14 Feb 16 2025 05:30:28
%S A197519 7,5,0,7,6,2,4,9,0,2,2,7,8,8,1,2,7,5,3,4,1,9,7,3,6,3,1,4,4,3,1,3,9,0,
%T A197519 7,8,5,6,8,2,5,7,2,2,6,5,3,6,1,7,0,5,6,2,8,1,9,2,4,9,7,2,1,3,0,1,6,8,
%U A197519 1,6,8,8,9,7,7,7,2,5,0,4,2,1,4,2,5,2,9,2,5,2,5,6,7,6,8,3,4,1,7
%N A197519 Decimal expansion of least x>0 having cos(2*Pi*x)=(cos 2x)^2.
%C A197519 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 A197519 This number is irrational. I cannot prove it to be algebraic or transcendental. - _Charles R Greathouse IV_, Feb 16 2025
%e A197519 0.7507624902278812753419736314431390785682572...
%t A197519 b = 2 Pi; c = 2; f[x_] := Cos[x]
%t A197519 t = x /. FindRoot[f[b*x] == f[c*x]^2, {x, .75, .76}, WorkingPrecision -> 200]
%t A197519 RealDigits[t] (* A197519 *)
%t A197519 Plot[{f[b*x], f[c*x]^2}, {x, 0, Pi/2}]
%Y A197519 Cf. A197476.
%K A197519 nonn,cons
%O A197519 0,1
%A A197519 _Clark Kimberling_, Oct 16 2011
%E A197519 Offset corrected by _Georg Fischer_, Jul 28 2021