Problem Statement

Semiprime numbers are natural numbers that are products of exactly two (possibly equal) prime numbers.

Semiprimes   are also known as:

(This particular number was chosen as the length of the Arecibo message).

Write a function determining whether a given number is semiprime.

Let's start with the solution:

func: semiprime(n)
| i |
   0 2 n sqrt asInteger for: i [ while(n i /mod swap 0 &=) [ ->n 1+ ] drop ]
   n 1 > ifTrue: [ 1+ ] 2 == ;