Numbers whose base-4 representation has 3 fewer 0's than 3's.

Terms

a(0) =63a(1) =127a(2) =191a(3) =223a(4) =239a(5) =247a(6) =251a(7) =253a(8) =254a(9) =383a(10) =447a(11) =479a(12) =495a(13) =503a(14) =507a(15) =509a(16) =510a(17) =639a(18) =703a(19) =735a(20) =751a(21) =759a(22) =763a(23) =765a(24) =766a(25) =831a(26) =863a(27) =879a(28) =887a(29) =891