If n appears so do 2n, 3n+2, 6n+3.

Terms

a(0) =1a(1) =2a(2) =4a(3) =5a(4) =8a(5) =9a(6) =10a(7) =14a(8) =15a(9) =16a(10) =17a(11) =18a(12) =20a(13) =26a(14) =27a(15) =28a(16) =29a(17) =30a(18) =32a(19) =33a(20) =34a(21) =36a(22) =40a(23) =44a(24) =47a(25) =50a(26) =51a(27) =52a(28) =53a(29) =54