pattern that was constructed by Dean Hickerson on November 1, 1991 that produces a stream of lightweight spaceships representing the prime numbers. N is prime if and only if a lightweight spaceship is above the honeycomb at the bottom-left corner of the pattern at generation 120N. It was the first pattern created that computes prime numbers, though others have since been constructed using the same ideas.
It works by using gliders to emulate a prime number sieve. Lightweight spaceships that move westward are deleted by gliders that represent positive integers if the lightweight spaceship represents a multiple of that number.