8-20 · prime form 01245789

One shape, its own mirror

steps 1 1 2 1 2 1 1 3

range 9 · 12 transpositions · 8 modes

Interval-class vector
ic1	ic2	ic3	ic4	ic5	ic6
5	4	5	6	6	2

Every set in the class holds five semitones, four whole tones, five minor thirds, six major thirds, six fourths and two tritones.

Common tones under Tn
T0	T1	T2	T3	T4	T5	T6	T7	T8	T9	T10	T11
8	5	4	5	6	6	4	6	6	5	4	5

Notes a set keeps when transposed by n.

Common tones under TnI
T0I	T1I	T2I	T3I	T4I	T5I	T6I	T7I	T8I	T9I	T10I	T11I
5	6	6	4	6	6	5	4	5	8	5	4

Notes a set keeps when inverted about n.

Set theory treats D# and Eb as one pitch class; the names under each set use one fixed spelling, sharps except Bb.

Complement

4-20 0158 · major seventh chord

Z-partner

none: no other class has this interval vector

Symmetry

T0 and one inversion map it onto itself

Inside it

2 notes: 2-1 ×5 · 2-2 ×4 · 2-3 ×5 · 2-4 ×6 · 2-5 ×6 · 2-6 ×2

3 notes: 3-1 ×2 · 3-2 ×4 · 3-3 ×8 · 3-4 ×8 · 3-5 ×6 · 3-6 ×2 · 3-7 ×6 · 3-8 ×4 · 3-9 ×4 · 3-10 ×2 · 3-11 ×8 · 3-12 ×2

4 notes: 4-2 ×2 · 4-3 ×2 · 4-4 ×4 · 4-5 ×2 · 4-6 ×2 · 4-7 ×3 · 4-8 ×2 · 4-9 · 4-10 · 4-11 ×2 · 4-12 ×2 · 4-13 ×2 · 4-14 ×4 · 4-Z15 ×4 · 4-16 ×4 · 4-17 ×3 · 4-18 ×4 · 4-19 ×8 · 4-20 ×3 · 4-22 ×4 · 4-23 ×3 · 4-24 ×2 · 4-26 ×2 · 4-27 ×2 · 4-Z29 ×2

5 notes: 5-3 ×2 · 5-6 ×2 · 5-7 ×2 · 5-10 ×2 · 5-11 ×2 · 5-13 ×2 · 5-14 ×4 · 5-16 ×2 · 5-Z17 ×2 · 5-Z18 ×2 · 5-19 ×2 · 5-20 ×2 · 5-21 ×6 · 5-22 ×2 · 5-23 ×2 · 5-26 ×2 · 5-27 ×2 · 5-29 ×2 · 5-30 ×4 · 5-32 ×2 · 5-35 ×2 · 5-Z36 ×2 · 5-Z37 ×2 · 5-Z38 ×2

6 notes: 6-Z6 · 6-Z11 ×2 · 6-Z13 · 6-14 ×2 · 6-15 ×2 · 6-16 ×2 · 6-Z17 ×2 · 6-18 ×2 · 6-Z19 ×2 · 6-20 · 6-Z24 ×2 · 6-31 ×2 · 6-32 · 6-Z44 ×2 · 6-Z47 ×2 · 6-Z48 ×2

7 notes: 7-20 ×2 · 7-21 ×2 · 7-27 ×2 · 7-Z38 ×2

Around it

9-4 ×2 · 9-11 ×2 · and 6 larger classes