Number of entries in n-th row of Pascal's triangle not divisible by 3.

Terms

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