- array_sum: documentation ( source)
- microtime: documentation ( source)
- array_values: documentation ( source)
<?php
$n = 80000;
$start = microtime(true);
$arr = array();
if ($n >= 2) $arr[] = 2;
for ($i = 3; $i<=$n; $i+=2) {
$arr[] = $i;
}
foreach ($arr as $key=>$row) {
foreach($arr as $key2=>$row2) {
if ($key2 > $key && ($row2 % $row) === 0) {
unset($arr[$key2]);
}
}
}
$arr = array_values($arr);
echo '<pre>';
echo array_sum($arr), PHP_EOL;
echo (microtime(true)-$start);