cpr_maker.php

<?php
function validate_cpr_number( $cpr ) {
	if ( empty( $cpr ) ) {
		return false;
	}
	$cpr = str_split( $cpr );
	$main_int = 0;
	$x = 0;
	$factors = [ 4, 3, 2, 7, 6, 5, 4, 3, 2, 1 ];
	foreach ( $cpr as $cpr_single_number ) {
		$main_int += $cpr_single_number * $factors[ $x ];
		$x++;
	}
	return $main_int % 11 == 0;
}

function generate_cprs(){
	$result = [];
	$date = "050287";
	$number = 0;
	for ($x = 0; $x < 10; $x ++) {
		for($y = 0; $y < 10; $y ++){
			for($z = 0; $z < 10; $z ++){
				for($i = 0; $i < 10; $i ++){
					$cpr = trim($date . $x . $y . $z . $i);
					echo $cpr . "\n";
					if(validate_cpr_number($cpr)){
						array_push($result, $cpr);
					}
				}
			}
		}
	}
	return $result;
}

print_r(generate_cprs());