#!/usr/bin/env perl

use strict;
use warnings;

my @f;

# Modification of your code
for my $i (0..2) {
    my @e = ($i+2, $i+1);
    push @f, [@e];
}

# A more succinct way to achieve it
for my $i (3..5) {
     push @f, [$i+2, $i+1];
}

# For demo purposes
use Data::Dump;
dd \@f;

##</code><code>##

[[2, 1], [3, 2], [4, 3], [5, 4], [6, 5], [7, 6]]