Write a PHP script to generate unique random numbers within a range

PHP is a server scripting language, and It is a powerful tool for making interactive and dynamic Web-pages. I have used WampServer 2.2 for following excercise..

<?php
$n=range(21,40);
shuffle($n);
for ($x=0; $x< 10; $x++)
{
echo $n[$x].'<br> ';
}
echo "<br>"
?>

Result:

35
37
24
33
39
30
32
38
34
27