re: #350 Backwoods_Sleuth

Definition per googling: In mathematics, a semiprime (also called biprime or 2-almost prime, or pq number) is a natural number that is the product of two (not necessarily distinct) prime numbers.

And my favorite part of mathematics: The cardinalities of those two sets, one the set of all primes, and the other the set of all semiprimes, are the same.