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x = 13, y = 12, rule = B3/S23 11b2o$11bo$9bobo$9b2o$5b2o$6bo$6bo$6b2o$2b2o$bobo$bo$2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ]] #C [[ GPS 2 ZOOM 16 LOOP 5 ]]
Pattern type Oscillator
Number of cells 20
Bounding box 13×12
Period 5
Mod 5
Heat 8.8
Volatility 0.65
Strict volatility 0.65
Discovered by Bill Gosper
Year of discovery 1977

Pentoad (or eater-bound Z-hexomino[1]) is a period-5 oscillator that was found by Bill Gosper in June 1977. It consists of a Z-hexomino that is stabilized by two eater 1s.

It was discovered by Scott Kim that this oscillator is extensible by moving one of the eaters diagonally away by four cells and inserting another Z-hexomino in the gap.[2] A pentoad constructed in this way with n Z-hexominoes has 14 + 6n cells and heat 8.8 + 6.4n. The pentoad with two Z-hexominoes is shown below.

goldenratio found a 10-glider synthesis of this oscillator on September 3, 2020.[3]

Image gallery

The pentoad with two Z-hexominoes.
Download RLE: click here

See also


  1. Mark D. Niemiec. "Eater-bound Z-hexomino glider synthesis RLE file". Retrieved on April 28, 2009.
  2. Dean Hickerson's oscillator stamp collection. Retrieved on March 14, 2020.
  3. goldenratio (September 3, 2020). Re: Synthesising Oscillators (discussion thread) at the forums

External links

  • 20P5.9 at Heinrich Koenig's Game of Life Object Catalogs