Special reptiles - repeating shapes and fractals

The Viper substitution tiling divides a particular triangle into 9 similar sub-triangles without reflection, in a non-trivial way. The same triangle can also be divided into 4 similar sub-triangles without reflection, see the top half of the triangle in the rule image on that page.

Imagine a Square, it can be divided into 4 smaller squares or 9 smaller squares,

So it is 4-rep and 9-rep.

4 and 9 are both coprime.