A number is an   attractive number   if the number of its prime factors (whether distinct or not) is also prime.



Example

The number   20,   whose prime decomposition is   2 × 2 × 5,   is an   attractive number   because the number of its prime factors   (3)   is also prime.



Task

Show sequence items up to   120.



Reference

   The OEIS entry:   A063989: Numbers with a prime number of prime divisors.


attractivenumbers := proc(n::posint)
local an, i;
an :=[]:
for i from 1 to n do
    if isprime(NumberTheory:-NumberOfPrimeFactors(i)) then
        an := [op(an), i]:
    end if:
end do:
end proc:
attractivenumbers(120);