A111939 Number of primes < semiprime(n).
2, 3, 4, 4, 6, 6, 8, 8, 9, 9, 11, 11, 11, 12, 12, 14, 15, 15, 16, 16, 16, 18, 18, 19, 21, 21, 22, 23, 23, 23, 24, 24, 24, 24, 27, 29, 30, 30, 30, 30, 30, 30, 31, 32, 32, 34, 34, 34, 34, 34, 36, 37, 37, 37, 38, 39, 40, 40, 42, 42, 42, 44, 46, 46, 46, 46, 46, 46, 47, 47, 47, 47, 47
Offset: 1
Keywords
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Programs
-
Mathematica
PrimePi@Select[Range@218, Plus @@ Last /@ FactorInteger@# == 2 &] (* Robert G. Wilson v, Jan 10 2006 *) PrimePi/@Select[Range[300],PrimeOmega[#]==2&] (* Harvey P. Dale, Nov 16 2014 *)
Extensions
More terms from Robert G. Wilson v, Lambert Herrgesell (zero815(AT)googlemail.com) and Matthew Conroy, Dec 16 2005
Entry revised by Ray Chandler, Sep 20 2006