Mandelbrot set for the sequence z(n+1) = cos(z(n)) + 1/c, with z(0) = 2.5*exp (iθ), θ between 0 and π

Mandelbrot set for the sequence z(n+1) = cos(z(n)) + 1/c, with z(0) = 2.5*exp (iθ), θ between 0 and π