OFFSET
1,1
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
FORMULA
a(n) ~ A033992(n) ~ 2n log n / (log log n)^2. - Charles R Greathouse IV, Jul 28 2016
EXAMPLE
2310=2*3*5*7*11 has 5 prime factors, hence it is not here, but it is part of A064040.
MATHEMATICA
Select[Range[106], MemberQ[{2, 3}, PrimeNu[#]]&] (* Jayanta Basu, Jun 04 2013 *)
PROG
(PARI) is(n)=my(o=omega(n)); o==2 || o==3 \\ Charles R Greathouse IV, Jul 28 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Dec 01 2009
STATUS
approved