Demienneract

The demienneract, or henne, also called the hemienneract or 9-demicube, is a convex uniform polyyotton. It has 18 demiocteracts and 256 enneazetta as facets, with 9 of each at a vertex forming a rectified enneazetton as the vertex figure. It is the 9-dimensional demihypercube and is formed by alternating the enneract. It is also a segmentoyotton, as a demioctactic antiprism.

Vertex coordinates
The vertices of a demienneract of edge length 1, centered at the origin, are given by all even sign changes of:
 * $$\left(\frac{\sqrt2}{4},\,\frac{\sqrt2}{4},\,\frac{\sqrt2}{4},\,\frac{\sqrt2}{4},\,\frac{\sqrt2}{4},\,\frac{\sqrt2}{4},\,\frac{\sqrt2}{4},\,\frac{\sqrt2}{4},\,\frac{\sqrt2}{4}\right).$$