$re = '/{\K(?:[^,}]*,){13}/';
$str = '{1,1,0,0,0,4,0,0,0,0,20,4099,4241,706,706,714,714,817,824,824,824,2,2,2,2,1,1,1,1},';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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