array(3) {
  [1]=>
  array(2) {
    [0]=>
    int(5521)
    [1]=>
    int(6123)
  }
  [9]=>
  array(1) {
    [0]=>
    int(6305)
  }
  [21]=>
  array(2) {
    [0]=>
    int(9601)
    [1]=>
    int(9621)
  }
}