Elkies' p5 is a period-5 oscillator that was found by Noam Elkies on June 16, 1997.
Elkies' p5 first occurred naturally in a soup found by Dave Greene using Adam P. Goucher's apgsearch program in April 2015. Other efforts from apgsearch allowed a 15-glider synthesis of an 18-cell still life which can be converted to Elkies' p5. This 20-glider synthesis was completed by Brett Berger and Martin Grant. This was further improved to 8 gliders by Brett Berger and Martin Grant following a second natural occurrence in January 2016.
On Catagolue, it is the third most common period 5 oscillator if stator variants are excluded, after octagon II and fumarole.
Use as a sparker
Elkies' p5 usually gets destroyed when trying to use it as a sparker, but it works in a few situations. One high-period example is this period-100 wing hassler. Note that two generations after being sparked, there is a two-cell leading edge in the sparker that matches the two cells in the active region.
- 20P5.11 at Heinrich Koenig's Game of Life Object Catalogs