#C A small spacefiller.
#C
#C Spacefillers are the fastest-growing known pattern in Conway's
#C Game of Life (probably the fastest possible).  They fill space
#C to a density of 1/2, conjectured to be the maximum density,
#C and they do it at a speed of c/2 in each of the 4 directions,
#C which has been proven to be the maximum possible speed.
#C
#C This pattern starts with 200 cells, not the record lowest number
#C of starting cells for a spacefiller (at the time of this writing,
#C the record is 151).  Quadratic-growth patterns that start with
#C as few as 20 ON cells are now known, but their growth rate is
#C comparatively slow.
#C
#C The population of spacefillers are easy to compute.  This one's
#C equations are:
#C
#C     [(t+17)^2+511]/4 for t divisible by 4;
#C     [(t+17)^2+608]/4 for t mod 4 = 1;
#C     [(t+17)^2+563]/4 for t mod 4 = 2;
#C     [(t+17)^2+580]/4 for t mod 4 = 3.
#C
#C Most spacefillers at this time have p2 stretchers on the left and
#C right instead of the flipper stretchers in this pattern.
#C
#C Original idea and middle part by Al Hensel; original construction
#C and top/bottom stretchers by Hartmut Holzwart; size optimization
#C by David Bell, Al Hensel, and Tim Coe.
#C
#C This spacefiller by Hartmut Holzwart, 4 Nov 1998.
#C From Alan Hensel's "lifebc" pattern collection.
#C
#C Updated 16 May 2022 -- source:
#C https://conwaylife.com/forums/viewtopic.php?p=148802#p148802
x = 49, y = 26, rule = B3/S23
20b3o3b3o$19bo2bo3bo2bo$4o18bo3bo18b4o$o3bo17bo3bo17bo3bo$o8bo12bo3bo
12bo8bo$bo2bo2b2o2bo25bo2b2o2bo2bo$6bo5bo7b3o3b3o7bo5bo$6bo5bo8bo5bo8b
o5bo$6bo5bo8b7o8bo5bo$bo2bo2b2o2bo2b2o4bo7bo4b2o2bo2b2o2bo2bo$o8bo3b2o
4b11o4b2o3bo8bo$o3bo9b2o17b2o9bo3bo$4o11b19o11b4o$16bobo11bobo$19b11o$
19bo9bo$20b9o$24bo$20b3o3b3o$22bo3bo2$21b3ob3o$21b3ob3o$20bob2ob2obo$
20b3o3b3o$21bo5bo!
