Those patterns of semicircles aren't random, of course. They correspond directly to the degree of compositeness of the chosen modulus. Compare for n = 60,61,62, for example.
The higher the totient value for n, the more circles you see, basically.
Right, so I can look at the diagram and see that 59 and 61 are prime while 60 has many divisors. I can kinda see that the density of primes decreases gradually.
Those patterns of semicircles aren't random, of course. They correspond directly to the degree of compositeness of the chosen modulus. Compare for n = 60,61,62, for example.
The higher the totient value for n, the more circles you see, basically.