Finding the first 10.000 primes in C#

        List<int> primes = new List<int>();
        int[] m = new int[] { 1, 3, 7, 9 };

        private bool isPrime(int n)
        {
            for (int i = 0; i < primes.Count; i++)
                if ((primes[i] <= Math.Round(Math.Sqrt(n)) + 1) && (n % primes[i] == 0))
                    return false;
            return true;
        }

        private void run()
        {
            int i = 2, d = 1;
            primes.Clear();
            while (primes.Count < 10000)
            {
                while (i < 10){
                    if (isPrime(i))
                        primes.Add(i);
                    i++;
                }
                for (int n = 0; n < 4; n++)
                {
                    i = d * 10 + m[n];
                    if (isPrime(i))
                        primes.Add(i);
                }
                d++;
            }
        }