Numbers whose base-7 representation has the same number of 0's as 6's.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =5a(5) =8a(6) =9a(7) =10a(8) =11a(9) =12a(10) =15a(11) =16a(12) =17a(13) =18a(14) =19a(15) =22a(16) =23a(17) =24a(18) =25a(19) =26a(20) =29a(21) =30a(22) =31a(23) =32a(24) =33a(25) =36a(26) =37a(27) =38a(28) =39a(29) =40