Interprime

In mathematics, an interprime is the average of two consecutive odd primes. For example, 9 is an interprime because it is the average of 7 and 11. 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, ... (sequence A024675 in the OEIS)

Interprimes cannot be prime themselves (otherwise the primes would not have been consecutive).

Since there are infinitely many primes, there are also infinitely many interprimes.

See also

References

  1. 1 2 Weisstein, Eric W. "Interprime". mathworld.wolfram.com. Retrieved 2020-08-10.