static void Main(string[] args)
{
for (int num = 2; num < 10000; num++)
{
if (IsPrime(num))
{
var b = num + 2;
if(IsPrime(b))
Console.WriteLine(num+"和"+b);
}
}
Console.ReadKey();
}
public static bool IsPrime(long num)
{
if (num < 2) return false;
if (num == 2 || num == 3) return true;
if (num % 6 != 1 && num % 6 != 5) return false;
int sqr = (int)Math.Sqrt(num);
for (int i = 5; i <= sqr; i += 6)
if (num % i == 0 || num % (i + 2) == 0)
return false;
return true;
}