Prime interval

"Proposal", see #Open questions

A prime interval is a musical interval which as a ratio of frequencies is a prime number; that is, a number such as 2, 3, 5, 7, ... which is divisible only by itself and 1. Any musical interval in the p-limit can be expressed in terms of a product of prime numbers less than or equal to p.

The prime intervals are 2/1, 1/2, 3/1, 1/3, 5/1, 1/5, 7/1, etc. The interval 5/3, for example, is not considered a prime interval.