1 1 5 1 2 1

11 5 1 2 1
1 15 1 2 1
1 1 51 2 1
1 1 5 12 1
1 1 5 1 21

function pc_permute($items, $perms = array( )) {
    if (empty($items)) {
        print join(' ', $perms) . "n";
    }  else {
        for ($i = count($items) - 1; $i >= 0; --$i) {
             $newitems = $items;
             $newperms = $perms;
             list($foo) = array_splice($newitems, $i, 1);
             array_unshift($newperms, $foo);
             pc_permute($newitems, $newperms);
         }
    }
}
print_r(pc_permute($ns));