a(n) = c([ n/3 ]) + n, with a(1) = 1, a(2) = 2, c = complement to a.

Terms

a(0) =1a(1) =2a(2) =6a(3) =7a(4) =8a(5) =10a(6) =11a(7) =12a(8) =14a(9) =15a(10) =16a(11) =21a(12) =22a(13) =23a(14) =28a(15) =29a(16) =30a(17) =35a(18) =36a(19) =37a(20) =39a(21) =40a(22) =41a(23) =43a(24) =44a(25) =45a(26) =47a(27) =48a(28) =49a(29) =54