Numbers whose base-7 representation has the same number of 3's and 4's.

Terms

a(0) =0a(1) =1a(2) =2a(3) =5a(4) =6a(5) =7a(6) =8a(7) =9a(8) =12a(9) =13a(10) =14a(11) =15a(12) =16a(13) =19a(14) =20a(15) =25a(16) =31a(17) =35a(18) =36a(19) =37a(20) =40a(21) =41a(22) =42a(23) =43a(24) =44a(25) =47a(26) =48a(27) =49a(28) =50a(29) =51