my @p;
sub part
{
   my ($a, $k, $n, $t) = @_;
   $n = 2*$k unless (defined($n));
   $t = 0    unless (defined($t));
   $p[$t] = $k;
   push(@$a, [ @p[1..$#p] ]) if $n == $k;
   for (my $j = $k<$n-$k ? $k : $n-$k; $j >= 1; $j--) {
      part($a, $j, $n-$k, $t+1);
   }
}


my $integer = ...;
my @a;
part(\@a, $integer);
print(join(" ", @$_), "\n") foreach (@a);