2.3.35 and 2.3.49

2.3.35 and 2.3.49 are two subsets of the 2.3.5.7 (septimal) group that involve many ratios further from 12edo than 2.3.7. The 35th harmonic (5*7) perfectly combines the deviations of the 5th and 7th harmonics to be about as far from 12edo as possible, whereas the 49th harmonic (7*7) overshoots slightly.

Intervals

(49/40 is a neutral third and doesn't exactly fit into either subgroup)

2.3.35

2.3.35 intervals are the difference between a 5-over and 7-under interval, or vice versa.

36/35 septimal quarter tone

35/32 septimal neutral second

81/70 septimal semifourth

2.3.49

2.3.49 intervals are the difference between a 7-over and 7-under interval.

54/49