Consider:

use strict;
use warnings;

my @powers = map{undef} 0 .. 3;
my $x = 2;

powers ($x, @powers);
print("$x @powers\n");


sub powers {
    $_[$_] = $_[$_ - 1] * $_[0] for 1 .. @_ - 1;
}
[download]

Prints:

2 4 8 16 32
[download]

Perl effectively passes parameters by reference. Arrays and hashes get flattened so each element becomes a parameter.