Numbers whose base-6 representation has the same nonzero number of 1's and 3's.

Terms

a(0) =9a(1) =19a(2) =39a(3) =51a(4) =54a(5) =56a(6) =58a(7) =59a(8) =63a(9) =69a(10) =81a(11) =91a(12) =109a(13) =114a(14) =116a(15) =118a(16) =119a(17) =121a(18) =133a(19) =139a(20) =153a(21) =163a(22) =189a(23) =199a(24) =219a(25) =231a(26) =234a(27) =236a(28) =238a(29) =239