a(n) = floor(n/2) - floor(n/3).

Terms

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