# XXX Doesn't handle negatives
sub idiv {
    my ($dividend, $divisor) = @_;
    use integer;
    my $quotient  = $dividend / $divisor;
    my $remainder = $dividend - ( $quotient * $divisor );
    return ( $quotient, $remainder );
}

my @chartab = (0..9, 'a'..'z');
my $N = 3;
for (0 .. @chartab**$N-1) {
    my $x = $_;
    for (1..$N) {
        ($x, my $i) = idiv($x, 0+@chartab);
        print $chartab[$i];
    }
    print ',';
}