using System.Collections.Generic;
public static void Main()
List<int> primes = new List<int>();
for(int num = a; num <= b; num++)
if(Math.Abs(num % 30) == 1 || Math.Abs(num % 30) == 7 ||
Math.Abs(num % 30) == 11 || Math.Abs(num % 30) == 13 ||
Math.Abs(num % 30) == 17 || Math.Abs(num % 30) == 19 ||
Math.Abs(num % 30) == 23 || Math.Abs(num % 30) == 29)
for(int i = 2; i <= Math.Sqrt(num); i++)
Console.WriteLine(String.Join(", ", primes));