# Semiprimes

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.

Semiprimes that are not perfect squares are called discrete, or distinct, semiprimes.

By definition, semiprime numbers have no composite factors other than themselves. For example, the number 26 is semiprime and its only factors are 1, 2, 13, and 26.

First 20: 4, 6, 9, 10, 14, 15, 21, 22, 25, 26, 33, 34, 35, 38, 39, 46, 49, 51, 55, 57

Checkout list of first: 10, 50, 100, 500, 1000 semiprimes. You can also check all semiprimes.

## Visualization#

Every frame counter is increased by one. If it is semiprime then dot appears. Color has no meaning. Video has 25fps.

You can also compare it with other types.

## External#

- OEIS: A001358
- Wikipedia: Semiprimes
- Youtube: Visualization up to 1 million