global

def colors
  @colors ||= (0...(6 * 7)).map do |n|
    pi_3 = Math::PI / 3
    n *= 1.0 / 6
    r  = (3 * Math.sin(n           ) + 3).to_i
    g  = (3 * Math.sin(n + 2 * pi_3) + 3).to_i
    b  = (3 * Math.sin(n + 4 * pi_3) + 3).to_i
    36 * r + 6 * g + b + 16
  end
end