#N 20p3.rle
#C https://conwaylife.com/wiki/Period_3_oscillators
#C https://conwaylife.com/patterns/20p3.rle
x = 15, y = 5, rule = B3/S23
11bobo$3b3obo2bo3bo$bo3bo3bo3bo$o3bo2bob3o$bobo!