More Fokker

I got a copy of Fokker's other "finity" article, the one on
3-dimensional periodicity blocks in the 3-5-7 lattice. Again, he only
discusses the cases with 12, 19, 22, 31, 41, and 53 notes. But I found
that his quite extensive list of "bridges", taken 3 at a time, leads to
many other "good" numbers like 27, 72, 171, and 270, as well as "bad"
ones (as ETs they're not consistent within the 7-limit).