Prime[Range[20]]
{2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71}
Select[Range[100,150], PrimeQ]
{101, 103, 107, 109, 113, 127, 131, 137, 139, 149}
PrimePi[8000] - PrimePi[7700]
30
Prime[10000]
104729