Richard Schroeppel wrote:

Dean Hickerson produced a Conway Life pattern in the 1980s which created a glider stream with gliders at (only) the prime numbered positions. Fun to watch.

Actually 1991. In 2005, Jason Summers built 3 more efficient patterns that do the same thing, but twice as fast. All are shown, in RLE format, at: http://www.math.ucdavis.edu/~dean/RLE/primer.html Dean Hickerson dean@math.ucdavis.edu