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Doo-dah is a period-21spaceship consisting of a weekender pulling a period-21 tagalong that was found by John Winston Garth on December 6, 2020. In its simplest phase, the tagalong part consists entirely of two R-pentomino descendants.[1][2] The spaceship was found using a combination of ikpx2 and apgsearch, with partial results from the former being inputted into the latter via ikpx2's "standard input" feature, with the goal of searching higher-period spaceships and puffers. Garth named the tagalong "doo-dah" after a nickname for his grandfather.[3]
x = 76, y = 28, rule = B3/S23
43bo12bo$42b3o10b3o$bo12bo26b5o8b5o$3o10b3o25b5o8b5o$3o10b3o26bo6b2o6b
o$43b3o3b2o3b3o$46bobo2bobo$3bo3b2o3bo7bo12bo14bo2bo8bo12bo$bob4o2b4ob
o4bobo10bobo11bo6bo5b3o10b3o$bob4o2b4obo3bo3bo8bo3bo11b6o5b5o8b5o$19bo
2bo8bo2bo12bo4bo5b5o8b5o$5b6o8bobo4b2o4bobo24bo6b2o6bo$4b2o4b2o8b3o3b
2o3b3o26b3o3b2o3b3o$4b2o4b2o11bo6bo32bobo2bobo$22bo2b4o2bo13b3o4b3o10b
o2bo$26b2o16bo3bo2bo3bo7bo6bo$3b3o4b3o10b3o2b3o13bo3bo2bo3bo8b6o$47bo
4bo11bo4bo$6bo2bo$5b2o2b2o31b2ob2o6b2ob2o$5bo4bo31bo2b2o2b2o2b2o2bo$b
2obo6bob2o28b2o4b2o4b2o$3ob2o4b2ob3o7bo6bo31b3o4b3o$o3bo2b2o2bo3bo6b3o
4b3o30bo2bo2bo2bo$b3o3b2o3b3o6bo2b2o2b2o2bo27bo12bo$2bo10bo6b3ob2o2b2o
b3o26bo5b2o5bo$21b5o2b5o27bo4bo2bo4bo$23bo6bo32bo6bo!
#C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]]
#C [[ WIDTH 720 HEIGHT 540 THEME Book ZOOM 8 X 0 Y -14 GPS 15 AUTOSTART T 0 PAUSE 2 T 105 PAUSE 2 LOOP 106 ]]
Two clean block puffers:[4] p42 (left), p21 (right) (click above to open LifeViewer)
A beehive puffer based on this spaceship was found the same day, seemingly independently by iNoMed[5] and GUYTU6J.[6] GUYTU6J also found a block puffer formed by adding a second weekender to the side of the p21 ship.[6] Both of these puffers can be either one- or two-sided. Various glider rakes have also been constructed.[7][8][9] On December 7, GUYTU6J and praosylen found several period-42 doo-dah-based spaceships.[10][11]
Goldtiger997 found that the p21 tagalong could be added to the weekender with six gliders,[13][2] while iNoMed found that each side could be turned into a beehive puffer with two gliders.[14][2] Finally, gooddogtyson and BlinkerSpawn found that the p21 ship could be converted both to and from a puffer with just one glider each way, on each side.[15][16]
x = 52, y = 29, rule = B3/S23
2bobo42bobo$3b2o42b2o$3bo44bo10$19bo12bo$18b3o10b3o$17b5o8b5o$17b5o8b
5o$18bo6b2o6bo$19b3o3b2o3b3o$22bobo2bobo$24bo2bo$22bo6bo$23b6o$23bo4bo
3$7b2o34b2o$bo6b2o32b2o6bo$b2o4bo36bo4b2o$obo46bobo!
#C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]]
#C [[ HEIGHT 460 ZOOM 8 X 0 Y -8 THEME Book GPS 10 AUTOSTART T 0 PAUSE 3 T 54 PAUSE 1 T 64 PAUSE 1 T 85 PAUSE 1 LOOP 126 ]]
