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:

my @primes = (3..60).grep: &is-prime;

print 'First four Giuga numbers: ';

put sort flat (2..4).map: -> $c {
    @primes.combinations($c).map: {
        my $n = [×] 2,|$_;
        $n if all .map: { ($n / $_ - 1) %% $_ };
    }
}