<?php //php 5.5.9

    $seri = array('2','2','2','0','6','8');

    $last = -1;
    $count = 0;
    foreach($seri as $key) {
        if($last == -1) $last = $key;
        if($key == $last) $count++;
        else break;
    }

    echo "İlk $count eleman seri oluşturmuş";
?>