A197516 Decimal expansion of least x>0 having cos(Pi*x)=(cos 2x)^2.

1, 7, 9, 8, 5, 9, 1, 0, 3, 7, 0, 2, 8, 6, 9, 8, 4, 4, 2, 7, 7, 5, 5, 7, 2, 9, 2, 8, 4, 5, 2, 1, 6, 1, 3, 1, 1, 7, 0, 8, 8, 7, 0, 5, 1, 1, 1, 7, 5, 7, 5, 5, 6, 1, 5, 0, 4, 0, 8, 7, 1, 5, 6, 4, 2, 6, 4, 7, 6, 4, 6, 4, 9, 7, 8, 2, 0, 0, 6, 9, 9, 0, 1, 9, 0, 4, 3, 4, 6, 4, 0, 4, 9, 1, 3, 8, 5, 3, 2

Offset: 1

Author

Clark Kimberling, Oct 16 2011

Keywords

• nonn
• cons

Comments

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.

This number is irrational. I cannot prove it to be algebraic or transcendental. - Charles R Greathouse IV, Feb 16 2025

Examples

			1.79859103702869844277557292845216131170...
		

Crossrefs

Cf. A197476.

Programs

Mathematica

b = Pi; c = 2; f[x_] := Cos[x]
t = x /. FindRoot[f[b*x] == f[c*x]^2, {x, 1.7, 1.8}, WorkingPrecision -> 200]
RealDigits[t]  (* A197516 *)
Plot[{f[b*x], f[c*x]^2}, {x, 0, 3}]