just primes

>>> n=10**6
>>> a = [1]*n
>>> a[0]=a[1]=0
>>> for k in range(n):
...   if a[k] == 1:
...     for i in range(2*k, n, k):
...       a[i] = 0
...
>>> len([i for i in range(n) if a[i]==1])
78498