Enneract

The enneract, or enne, also called the 9-cube or octadecayotton, is one of the 3 regular polyyotta. It has 18 octeracts as facets, joining 3 to a hexeract peak and 9 to a vertex.

It is the 9-dimensional hypercube. It is also a cube trioprism.

It can be alternated into a demienneract, which is uniform.

Vertex coordinates
The vertices of an enneract of edge length 1, centered at the origin, are given by:
 * $$\left(\pm\frac12,\,\pm\frac12,\,\pm\frac12,\,\pm\frac12,\,\pm\frac12,\,\pm\frac12,\,\pm\frac12,\,\pm\frac12,\,\pm\frac12\right).$$