For example, 21 is an interprime since it is the average of the two consecutive primes 19 and 23.

The smallest 3 × 3 magic square whose entries are consecutive interprime numbers is

The first interprimes are 4, 6, 9, 12, 15, 18, 21, 26, 30, 34, 39, 42, 45, 50, 56, 60, 64, 69, 72, 76, 81, 86, 93, 99, 102, 105, 108, 111, 120 more terms

Pictorial representation of remainders (mod 2, 3, ...,11) frequency. For a table of values and more details click here

A graph displaying how many interprime numbers are multiples of the primes p from 2 to 71. In black the ideal line 1/p.