Numbers whose base-4 representation has the same number of 1's, 2's and 3's.

Terms

a(0) =0a(1) =27a(2) =30a(3) =39a(4) =45a(5) =54a(6) =57a(7) =75a(8) =78a(9) =99a(10) =108a(11) =114a(12) =120a(13) =135a(14) =141a(15) =147a(16) =156a(17) =177a(18) =180a(19) =198a(20) =201a(21) =210a(22) =216a(23) =225a(24) =228a(25) =267a(26) =270a(27) =291a(28) =300a(29) =306