Number of numbers <= n whose set of prime factors is a subset of the set of prime factors of n.

Terms

a(0) =1a(1) =2a(2) =2a(3) =3a(4) =2a(5) =5a(6) =2a(7) =4a(8) =3a(9) =6a(10) =2a(11) =8a(12) =2a(13) =6a(14) =5a(15) =5a(16) =2a(17) =10a(18) =2a(19) =8a(20) =5a(21) =7a(22) =2a(23) =11a(24) =3a(25) =7a(26) =4a(27) =8a(28) =2a(29) =18