Generate random numbers without repeat and sequence

I want to generate a random 4 digit pin without repeat and sequence numbers. I have tried the below code but it only preventing repeat numbers, it is still returning sequence numbers.

function randomGen($min, $max, $quantity) {
    $numbers = range($min, $max);
    shuffle($numbers);
    return array_slice($numbers, 0, $quantity);
}

$random = randomGen(1,9,4); 

$random_no = "";
foreach($random as $int){
 $random_no.=$int;   
}

$random_no = intval($random_no);

expected output : 4759

Should not be like this 5537 and 7312