A 20 tone well tempered nonet (20WTN) is related to well temperaments of 17edo and 18edo, but with a nonet rather than the 2/1 being constant. Its patent tunings alternate division of the just perfect fifth into 10 equal parts (10EDF) with sequences of ten equal steps of 60 to 80 cents each. This will create ten equally-spaced intervals between an interval between 600 and 800 cents and the just perfect fifth.

Optimal Intervals

Target Minimum a Target Maximum a Target Minimum b Target Maximum b
1 70.1955
2 140.391
3 210.5865
4 280.782
5 350.9775
6 421.173
7 491.3685
8 561.564
9 631.7595
10 701.955
11 773.104 764.511
12 844.253 826.0675
13 915.403 888.722
14 986.552 950.9775
15 1057.701 1012.233
16 1128.896 1075.489
17 1200 1137.744
18 1260 1280 1200
19 1320 1360 1260 1280
20 1380 1440 1320 1360