20:25:28:35 is a condissonant chord in the 7-limit and a possible interpretation of the French sixth chord.

Chord information
Harmonics 20:25:28:35
Subharmonics 1/(35:28:25:20)
Intervals from root 1/15/47/57/4
Cents from root 386¢583¢969¢
Step intervals 5/4, 28/25, 5/4
Step cents 386¢, 196¢, 386¢
Color names yo zo-7 zogu-5 or y,z7(zg5)
har-7 zogu-5 or h7(zg5)
Prime limit 7
Genus 527 (175)
Intervallic odd limit 25
Otonal odd limit 35
Utonal odd limit 35
Consistent edos (d ≥ 2) 6edo*, 25edo*, 31edo**, 37edo*, …

In marvel temperament, it is tuned identically to 128:160:180:225; in starling, it is tuned identically to 72:90:100:125; and in septimal meantone it is tuned the same as both of those. In all of those temperaments, it becomes an essentially tempered chord in the 9-odd-limit due to the ~28/25 interval being equated with either 9/8 or 10/9.


Edo approximations for 20:25:28:35 
intervals: 5/4, 7/5, 7/4 · ≤ 60edo, RMS rel. error ≤ 15%
  Edo Steps Cents (¢) Absolute errors (¢) RMS (¢) RMS (%)
6 0  2  3  5 0.00 400.00 600.00 1000.00 0.00 +13.69 +17.49 +31.17 11.10 5.55
10 0  3  5  8 0.00 360.00 600.00  960.00 0.00 -26.31 +17.49  -8.83 15.80 13.16
12 0  4  6 10 0.00 400.00 600.00 1000.00 0.00 +13.69 +17.49 +31.17 11.10 11.10
16 0  5  8 13 0.00 375.00 600.00  975.00 0.00 -11.31 +17.49  +6.17 10.41 13.89
19 0  6  9 15 0.00 378.95 568.42  947.37 0.00  -7.37 -14.09 -21.46 7.95 12.59
25 0  8 12 20 0.00 384.00 576.00  960.00 0.00  -2.31  -6.51  -8.83 3.46 7.20
31 0 10 15 25 0.00 387.10 580.65  967.74 0.00  +0.78  -1.87  -1.08 1.01 2.62
35 0 11 17 28 0.00 377.14 582.86  960.00 0.00  -9.17  +0.34  -8.83 4.59 13.38
37 0 12 18 30 0.00 389.19 583.78  972.97 0.00  +2.88  +1.27  +4.15 1.57 4.85
41 0 13 20 33 0.00 380.49 585.37  965.85 0.00  -5.83  +2.85  -2.97 3.24 11.08
43 0 14 21 35 0.00 390.70 586.05  976.74 0.00  +4.38  +3.53  +7.92 2.82 10.09
47 0 15 23 38 0.00 382.98 587.23  970.21 0.00  -3.33  +4.72  +1.39 2.89 11.32
50 0 16 24 40 0.00 384.00 576.00  960.00 0.00  -2.31  -6.51  -8.83 3.46 14.40
53 0 17 26 43 0.00 384.91 588.68  973.58 0.00  -1.41  +6.17  +4.76 3.16 13.97
56 0 18 27 45 0.00 385.71 578.57  964.29 0.00  -0.60  -3.94  -4.54 1.99 9.30