$re = '/(\s?\d\s?)(\s?\1){2,}/m';
$str = '611 1 1256 8856 55 55
2 3 3 3 3 11 222 0 1 2 88 8 811';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php