private void NextPrime()
{
int p = primes[primes.Count - 1] + 1;
while (p < m + n && bits[p - m])
{
++p;
}
if (p == m + n)
{
if (m > maximumSize)
{
throw new InvalidOperationException("too many primes");
}
m += n;
n *= 2;
bits = new Word64BitArray(n);
for (int i = 0; i < primes.Count; i++)
{
Sieve(primes[i]);
}
while (p < m + n && bits[p - m])
{
++p;
}
}
Sieve(p);
primes.Add(p);
}
public SieveOfEratosthenes()
{
bits = new Word64BitArray(initialSize);
bits[0] = true;
bits[1] = true;
m = 0;
n = initialSize;
primes = new List <int>();
primes.Add(2);
Sieve(2);
}