17-3 step prism

The 17-3 step prism is a convex isogonal polychoron and a member of the step prism family. It has 85 phyllic disphenoids of five kinds as cells, with 20 joining at each vertex. It can also be constructed as the 17-6 step prism.

Vertex coordinates
Coordinates for the vertices of a 17-3 step prism inscribed in a heptadecagonal duoprism with base lengths a and b are given by: where k is an integer from 0 to 16. If the edge length differences are to be minimized, the ratio of a:b must be equivalent to 1:$$\sqrt{\frac{\cos\frac{5\pi}{17}+\cos\frac{2\pi}{17}}{\cos\frac{2\pi}{17}-\cos\frac{6\pi}{17}}}$$ ≈ 1:1.77592.
 * (a*sin(2πk/17), a*cos(2πk/17), b*sin(6πk/17), b*cos(6πk/17)),