x = 21, y = 10, rule = B3678/S34678
3boo$3b5obooboo$bobob4obboobb3o$boo3boob5oboboboo$obobooboobb6obboo$ob
obooboobb6obboo$boo3boob5oboboboo$bobob4obboobb3o$3b5obooboo$3boo!
A period 4 c/4 orthogonal spaceship.
David Eppstein, April 1998
