x = 21, y = 12, rule = B3678/S34678
6bo$5boboboo$3bob6o6bo$bb8obo3b6o$b10obb6obo$20o$20o$b10obb6obo$bb8obo
3b6o$3bob6o6bo$5boboboo$6bo!
A period 20 c/2 spaceship.
This is related to the period 40 spaceship.
David I. Bell, April 1997
