OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
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 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Giovanni Teofilatto, Nov 27 2005
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
STATUS
approved