1729/1728
1729/1728, the massma, is a 19-limit superparticular interval and an unnoticeable comma.
Both the numerator and denominator of this interval are famous in mathematics. 1728, being 12 to the 3rd power, is also known as mass. 1729 is known for being the first number that can be expressed as a sum of more than 1 integer cubes.