Prime Spiral: Sieve of Eratosthenes

Video 1200 x 1200 pixels, duration 3:42

The video shows the Sieve of Eratosthenes in action, a method for discovering primes numbers.

All numbers are first assumed to be prime and drawn in black, except the number one which is not prime and drawn in white.
Then all those with factors are systematically eliminated.
In the end...

Prime numbers remain black
Numbers with one prime factor are green
Numbers with two prime factors are blue
Numbers with three prime factors are red
Numbers with four prime factors are grey

The number at the end of the spiral is 807 and is prime.

The palette is inspired by Jackson Pollock's Shorthand Figure, 1942

Algorithm
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