A polyiamond tri-oddity
is a figure with ternary symmetry formed by some number of copies of
a polyiamond that is not a multiple of three.
Torsten Sillke first studied them in 1996.
Here are the minimal known tri-oddities for heptiamonds (7-iamonds).
Unsolved heptiamonds are shown in grey.
Please write if you find a smaller solution or solve an unsolved case.
For polyiamonds with fewer than 7 cells, see
For polyhexes, see Polyhex Tri-Oddities.
These solutions have horizontal mirror symmetry as well as ternary symmetry.
Last revised 2017-09-02.
Back to Polyform Oddities
Col. George Sicherman