This is the same as above except that numbers along diagonals running SW to NE have the same color. Color by ring number Ring 1 is the central number. Ring 2 consists of the eight numbers surrounding this, ring 3 consists of the 16 numbers surrounding ring 2, and so on. The two numbers are often not equal. The Palmen color of a number is explained in Karl Palmen's Colours of Numbers .
All prime numbers are either red, green, blue or black.
For this reason a white background is used instead of the usual black. There are four ways to do this. The graphics display is automatically updated. This, however, is the maximum refresh rate. This gives a distribution of random numbers which mimics that of the primes.