Figure eight on pentadecathlon

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Figure eight on pentadecathlon
x = 14, y = 10, rule = B3/S23 bo6b2o$bo6b2obo$obo9bo$bo7bo$bo8bob2o$bo10b2o$bo$obo$bo$bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ]] #C [[ GPS 15 ZOOM 16 LOOP 120 ]]
Pattern type Oscillator
Number of cells 24
Bounding box 19 × 16
Period 120
Mod 120
Heat 38.9
Volatility 1.00
Strict volatility 0.01
Discovered by Unknown
Year of discovery Unknown

Figure eight on pentadecathlon can refer to one of two very closely related period-120 oscillator composed of a figure eight and pentadecathlon. The version detailed in the infobox to the right is the cis-version.

Although composed of two oscillators of smaller periods (8 and 15 respectively), they are considered non-trivial, due to containing one cell that is alive in generation 95 and dead in the other 119 phases of the oscillator. In terms of its 24 cells, they are the smallest known non-trivial period-120 oscillators, with the cis- version being the outright smallest when also considering the bounding box size.

Image Name apgcode Cost in gliders
Cisfigureeightonpentadecathlon.png Cis-figure eight on pentadecathlon xp120_4r4y13bg2kgz4r4y511 7
Transfigureeightonpentadecathlon.png Trans-figure eight on pentadecathlon xp120_vtvz757y1ssszy7777 7


26-cell variants

Alongside the two aforementioned 24-cell versions of the figure-eight-on-pentadecathlon, there are also two ways to combine a figure eight and a pentadecathlon into an oscillator with 26 cells in its minimum phase, which have 3 cells which oscillate with period 120.

Two of the period-120 cells are highlighted in the images in the below table; other pictures which display the third cell can be seen below it.

Image Name apgcode Cost in gliders
Cisfigureeightonpentadecathlonv2.png Cis-figure eight on pentadecathlon v2 xp120_gk2gb3y14evy2ve4z11 7
Transfigureeightonpentadecathlonv2.png Trans-figure eight on pentadecathlon v2 xp120_xsssy375777757z777 7


The cis variant first appeared in an asymmetric soup on March 3, 2019, in a haul submitted to Catagolue by benetnasch85.[1] This makes it the highest period oscillator to have occurred naturally.[2] The trans variant later appeared naturally on February 20, 2021, in a soup by Adam P. Goucher.

See also


  1. testitemqlstudop (March 3, 2019). Re: Soup search results (discussion thread) at the forums
  2. Adam P. Goucher. "Statistics". Catagolue. Retrieved on March 3, 2019.