x = 21, y = 19, rule = B3678/S34678
10bo$$10bo$$10bo$5boo7boo$10bo$3b7ob7o$b4obb7obb4o$b9ob9o$5obb7obb5o$
oob7ob7oboo$10bo$5boo7boo$10bo$$10bo$$10bo!
A period 20 spark oscillator.
The large spark can become a two bit spark if the central column is duplicated.
Dean Hickerson, April 1997
