Problem Statement

A Giuga number is a composite number n which is such that each of its distinct prime factors f divide (n/f - 1) exactly. All known Giuga numbers are even though it is not known for certain that there are no odd examples. 30 is a Giuga number because its distinct prime factors are 2, 3 and 5 and:

Determine and show here the first four Giuga numbers. Determine the fifth Giuga number and any more you have the patience for.

Let's start with the solution:

giuga?: function [n]->
    and? -> not? prime? n
         -> every? factors.prime n 'f
            -> zero? (dec n/f) % f

print.lines select.first:4 1..∞ => giuga?