Code related to a new vertex-transitive network topology.

The m-bit network has nodes corresponding to m-digit numbers in a
[mixed base](https://en.wikipedia.org/wiki/Mixed_radix)
system using
[Sylvester's sequence](https://en.wikipedia.org/wiki/Sylvester%27s_sequence)
as the base.

Directed edges correspond to the operation of incrementing the k lowest
digits by 1 and adding their new value to the next highest digit.