#MCell 2.0
#GAME Generations
#RULE 345/2/4
#BOARD 200x200
#SPEED 0
#WRAP 0
#D This shows a method of constructing guns of every even period from 20 onwards.
#D The example shown has period 42.
#D 
#D Stephen Silver, April 1999
#L 21.A$20.3A$21.A5$23.A$22.3A$21.AA.AA$22.3A$24.A$23.3A$24.A$$20.CBA$.A
#L 18.CBA$3A$.A$.3A$AA.AA$.3A$..A