function primeMultiples($int)
{
$largestPrime = 0;
$primes = getPrimes(10000);
foreach ($primes as $prime) {
$check = $int % $prime;
if ($check == 0 && $prime > $largestPrime) {
$largestPrime = $prime;
}
}
return $largestPrime;
}
$check = __primeCheck($primes, $int);
if ($check == TRUE) {
$primes[] = $int;
$length++;
}
$int++;
break;
}
}
return $primes;
}
/**
*
* Checks if a number is a prime or not.
* @param int $num
*/
function __primeCheck($primes, $num)
{
if ($num == 2) {
return TRUE;
}
foreach ($primes as $prime) {
$primeCheck = $num % $prime;
if ($primeCheck == 0) {
return FALSE;
}
}
return TRUE;
}
$primes = getPrimes(10001);
print $primes[10000];
if ($primeCheck == 0) {
return FALSE;
}
}
return TRUE;
}
function highestMultiplePrimes($primes, $max)
{
foreach ($primes as $prime) {
$int = $prime;
while ($int + $prime <= $max) {
$int = $int + $prime;
}
$numbers[] = $int;
}
$numbers = array_unique($numbers);
return $numbers;
}
function multiply($numbers)
{
$result = 1;
foreach ($numbers as $number) {
$result = $result * $number;
}
return $result;
}
$max = 20;
$primes = getPrimes($max);
$numbers = highestMultiplePrimes($primes, $max);
$result = multiply($numbers);
print "{$result}";
}
}
function tPrime($n)
{
$len = strlen($n);
for ($i = 2; $i <= $len; $i++) {
if (isPrime(substr($n, 0, $i)) && isPrime(substr($n, strlen($n) - $i, $i))) {
} else {
return false;
}
}
return true;
}
$n = 23;
$tPrimes = array();
getPrimes(50);
while (count($tPrimes) < 11) {
if (tPrime($n)) {
if (isPrime($n)) {
$tPrimes[] = $n;
echo ".";
}
}
$n++;
while (!in_array(substr($n, 0, 1), array(2, 3, 5, 7)) || !in_array(substr($n, strlen($n) - 1, 1), array(2, 3, 5, 7))) {
$n++;
}
}
echo "\n";
$total = array_sum($tPrimes);
result(748317, $total);
