21P4.1

21P4.1
x = 12, y = 7, rule = B3/S23 5bo$5bobo$4bo$2b3o3bo$6bob3o$o2b2o4bobo$2o8b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ]] #C [[ TRACKLOOP 4 0 0 GPS 2 THUMBSIZE 2 ]]
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Pattern type	Oscillator
Number of cells	21
Bounding box	12 × 7
Period	4 (mod: 2)
Heat	17
Volatility	0.81 | 0.81
Kinetic symmetry	n-e
Discovered by	Unknown
Year of discovery	Unknown
Rules Outer-totalistic rules B3/S23 – B378/S2378 # of rules 24 = 16 Isotropic rules B3-ceik/S2-ci3ajnqr – B2i34-airty5-jr6-n78/S234-ajnqr5-nq6-a78
Glider synthesis Fewest gliders 24† Catagolue-generated RLE synthesis †Can be constructed with 15 gliders using the reverse caber tosser universal constructor.
Pattern files Plaintext 21p4.1.cells RLE 21p4.1.rle
Identifiers apgcode xp4_39qozwie671z33 Pentadecathlon ID 21P4.1

21P4.1 is a period-4 oscillator. Although the sparks it gives off are relatively difficult to access, its small size means it is occasionally used in LCM oscillators such as twin bees shuttle on 21P4.1, which was formerly the smallest known p92 oscillator by population. It has since been superseded by mold on twin bees shuttle, which has a minimum population of 44 cells.

Martin Grant and MathAndCode found a 25-glider synthesis of this oscillator on August 23, 2021.

Gallery

x = 25, y = 17, rule = B3/S23 18b2o$18bobo$19b2o$20b2o$23bo$5b2o7bobo3bo$6bo7bo2bo5b2o$3bo10bobo2bob 2o$3bobo13bobo$2b2obo2bobo10bo$2o5bo2bo7bo$4bo3bobo7b2o$bo$3b2o$4b2o$ 4bobo$5b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ GPS 8 THUMBSIZE 2 ]]

A period-24 oscillator that uses 21P4.1 as a non-LCM sparker; originally stabilized with heavyweight emulators by Jason Summers on April 12, 2008 (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here

External links

• 21P4.1 at Adam P. Goucher's Catagolue
• 21P4.1 at Heinrich Koenig's Game of Life Object Catalogs