Numbers with exactly four distinct base-6 digits.

Terms

a(0) =231a(1) =232a(2) =233a(3) =236a(4) =238a(5) =239a(6) =242a(7) =243a(8) =245a(9) =248a(10) =249a(11) =250a(12) =291a(13) =292a(14) =293a(15) =306a(16) =310a(17) =311a(18) =312a(19) =315a(20) =317a(21) =318a(22) =321a(23) =322a(24) =326a(25) =328a(26) =329a(27) =336a(28) =340a(29) =341