Almost Not
(...)
And here’s another almost not progression with three four-note chords, where the adjacent notes are always separated by two major seconds and one fourth. The three chords belong to two different Forte sets, but they have the same top and bottom notes, and their sums, which are 29, 26, and 23, are all equivalent to 2 modulo 3. One could also no doubt number the notes in such a way that these three chords would become part of some block design. In this case the chords don’t make a circle, but you can follow the arrows however you like to make almost not progressions at each move.(...)
Three four-note chords in an almost-not progression
