[ Posted by Biswa Bandhu Bhandary ] This code generates the below pattern if we set modulus divider value 3 i = 0;j = 0; i = 1;j = 0; i = 2;j = 0; i = 3;j = 1; i = 4;j = 1; i = 5;j = 1; i = 6;j = 2; i = 7;j = 2; so on...

fiddle_029528.php

<?php
$i = 0;
$_SESSION['k'] = 0;


while ($i<1000){
    do_mail($i);
    $i++;
}

function do_mail($i) {
    $j = 0;
    $k = $_SESSION['k'];
    echo "i->".$i;
    if ($i%500 === 0 && $i !== 0){
        $k += 1;
        $_SESSION['k'] = $k;
    }
    $j = $i-($i-$k);
    echo "j->".$j."</br>";
}
?>