function FindPrime($ending)
{
    $primes = array(2);
    $i = 3;
    while (true) {
        if (Prime($i)) {
            array_push($primes, $i);
            if (count($primes) == $ending) {
                echo end($primes);
                break;
            }
        }
        $i += 2;
    }
}
Example #2
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            $count = 1;
            $primeNumber = 2;
        }
    } else {
        $count = 2;
        $primeNumber = 3;
    }
    for ($k = 5; $count < $n; $k += 2) {
        if (($k + 1) % 6 == 0 || ($k - 1) % 6 == 0) {
            $isTrivial = True;
            $limit = ceil(sqrt($k));
            for ($i = 5; $i <= $limit; $i += 2) {
                if ($k % $i == 0) {
                    $isTrivial = False;
                    break;
                }
            }
            if ($isTrivial) {
                $count++;
                $primeNumber = $k;
            }
        }
    }
    return $primeNumber;
}
$n = $argv[1];
printf("1st prime is %d\n", Prime(1));
printf("2nd prime is %d\n", Prime(2));
for ($i = 10 * $n; $i <= 50 * $n; $i += 10 * $n) {
    printf("%dth prime is %d\n", $i, Prime($i));
}