public static int NumberOfPrimeUnder(int number)
{
int result = 0;
for (int i = 2; i <= number; i++)
{
if (FunctionsMath.IsPrime(i))
{
result++;
}
}
return(result);
}
public static List <int> GetPrimesBefore(int number)
{
List <int> result = new List <int>
{
2
};
for (int i = 3; i <= number; i = i + 2)
{
if (FunctionsMath.IsPrime(i))
{
result.Add(i);
}
}
return(result);
}
public static Dictionary <int, int> NumberOfPrimesByHundred(int number)
{
Dictionary <int, int> result = new Dictionary <int, int>();
for (int i = 2; i <= number; i++)
{
if (FunctionsMath.IsPrime(i))
{
int index = (Math.Abs(i / 100) + 1) * 100;
if (result.ContainsKey(index))
{
result[index]++;
}
else
{
result.Add(index, 1);
}
}
}
return(result);
}
public static bool IsTwinPrime(int number)
{
return(FunctionsMath.IsPrime(number) && FunctionsMath.IsPrime(number + 2));
}