Prime Formula

by michiganfootball20

HTML

<html>
<head>
<title>Online PHP Script Execution</title>
</head>
<body>
<?php
   function buildPrimeArray($n){
     $ints = array();
     $primes = array(2);
    for($i = 1; $i < $n; $i++) $ints[$i] = true;
    
    //Loop through possible i values
    for($i = 1; $i < (sqrt(2*$n+1)-1)/2; $i++){
      //Loop through possible j values
      for($j = $i; $j < (($n-$i)/(2*$i+1)); $j++){
        $ints[intVal($i+$j+2*($i*$j))] = false;
      }
      
    } 
    foreach($ints as $val => $bool) {
      if($bool) $primes[] = 2*$val+1;
    }
    
    return $primes;
   }
   
  $primes = buildPrimeArray((2000000-1)/2);
  
  $count = 0;
  for($i = 0; $i < count($primes); $i++) $count += $primes[$i];
  
  echo $count;
  
?>
</body>
</html>