Number of composite numbers <= n and relatively prime to n.

Terms

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