Numbers whose base-4 representation has the same number of 1's and 3's.

Terms

a(0) =0a(1) =2a(2) =7a(3) =8a(4) =10a(5) =13a(6) =19a(7) =27a(8) =28a(9) =30a(10) =32a(11) =34a(12) =39a(13) =40a(14) =42a(15) =45a(16) =49a(17) =52a(18) =54a(19) =57a(20) =67a(21) =75a(22) =76a(23) =78a(24) =95a(25) =99a(26) =107a(27) =108a(28) =110a(29) =112