Odd prime sum limit

The n-odd-prime-sum-limit (abbreviated n-OPSL) is the collection of all just ratios where the no-twos sum of prime factors with repetition of both the numerator and the denominator does not exceed the integer n.

This concept was noted by Tristan Bay as a way to measure how accurately an edo approximates just intonation with lower primes weighted more heavily. Specifically, the idea is to use OPSLs as an alternative metric for consistency limit either instead of or alongside odd limits.

Comparison with odd limit

The 1- and 2-odd-prime-sum-limit are equivalent to the 1-odd-limit, which only contains a single interval pair {1/1, 2/1}. The 3- and 4-odd-prime-sum-limit are equivalent to the 3-odd-limit, which adds {3/2, 4/3}. All edos are consistent in those limits.

The 5-odd-prime-sum-limit adds {5/4, 8/5} without {5/3, 6/5} from the 5-odd-limit, so it is the first OPSL that differs from the corresponding odd limit. The 6-odd-prime-sum-limit adds {9/8, 16/9}. The 7-odd-prime-sum-limit adds {7/4, 8/7} without {7/6, 12/7}, and the 8-odd-prime-sum-limit adds {5/3, 6/5} as well as {15/8, 16/15}. The 9-odd-prime-sum-limit adds {27/16, 32/27}, and the 10-odd-prime-sum-limit adds {7/6, 12/7}, {21/16, 32/21}, and {25/16, 32/25}. The 11-odd-prime-sum-limit adds {11/8, 16/11}, {9/5, 10/9}, and {45/32, 64/45}. The 12-odd-prime-sum-limit adds {7/5, 10/7}, {35/32, 64/35} and {81/64, 128/81}.

Minimal OPSL-consistent edos

OPSL	Smallest Consistent Edo*
1	1
2	1
3	1
4	1
5	3
6	3
7	5
8	12
9	12
10	12
11	31
12	72
13	72
14	130
15	270
16	270
17	954
18	1236
19	1578
20	1578
21	3395
22	3395
23	6079
24	8539
25	8539
26	8539
27	8539
28	102557
29	102557
30	102557
31	102557
32	102557
33	258008
34	258008
35	258008
36	258008

*apart from 0edo

Whole-interval OPSL

The n-whole-interval-OPSL, or n-WOPSL, is slightly different from the n-OPSL. This is the collection of all just ratios with a no-twos Wilson height that does not exceed the integer n. It was confused with the original definition for n-OPSL at the time of this Wiki article's creation, but has since been corrected.

Comparison between odd-limit and WOPSL

The 1- and 2-WOPSL are equivalent to the 1-odd-limit, which only contains a single interval pair {1/1, 2/1}. The 3- and 4-WOPSL are equivalent to the 3-odd-limit, which adds {3/2, 4/3}. All edos are consistent in those limits.

The 5-WOPSL adds {5/4, 8/5} without {5/3, 6/5} from the 5-odd-limit, so it is the first WOPSL that differs from the corresponding odd limit. The 6-WOPSL adds {9/8, 16/9}. The 7-WOPSL adds {7/4, 8/7} without {7/6, 12/7}, and the 8-WOPSL adds {5/3, 6/5} as well as {15/8, 16/15}. The 9-WOPSL adds {27/16, 32/27}, and the 10-WOPSL adds {7/6, 12/7}, {21/16, 32/21}, and {25/16, 32/25}. The 11-WOPSL adds {11/8, 16/11}, {9/5, 10/9}, and {45/32, 64/45}. The 12-WOPSL adds {7/5, 10/7}, {35/32, 64/35} and {81/64, 128/81}.