Numbers with exactly three distinct base-4 digits.

Terms

a(0) =18a(1) =19a(2) =24a(3) =27a(4) =28a(5) =30a(6) =33a(7) =35a(8) =36a(9) =39a(10) =44a(11) =45a(12) =49a(13) =50a(14) =52a(15) =54a(16) =56a(17) =57a(18) =66a(19) =67a(20) =70a(21) =71a(22) =72a(23) =73a(24) =74a(25) =76a(26) =77a(27) =79a(28) =82a(29) =83