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semiprime numbers

A semiprime is a natural number that is the product of exactly two prime numbers.

The first few semiprime numbers are: 4, 6, 9, 10, 14, 15, 21, 22, 25, 26, 33, 34, …

210,035 of the first one million positive integers are semiprime.

Learn more about semiprime numbers on wikipedia.

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