All-trichord hexachord

1. How many Trichords are there?
2. What is the all interval tetrachord?

How many Trichords are there?

A trichord is a contiguous three-note set from a musical scale or a twelve-tone row. In musical set theory there are twelve trichords given inversional equivalency, and, without inversional equivalency, nineteen trichords.

What is the all interval tetrachord?

An all-interval tetrachord is a tetrachord, a collection of four pitch classes, containing all six interval classes. There are only two possible all-interval tetrachords (to within inversion), when expressed in prime form. In set theory notation, these are [0,1,4,6] (4-Z15) and [0,1,3,7] (4-Z29).