Numbers with exactly three distinct base-7 digits.

Terms

a(0) =51a(1) =52a(2) =53a(3) =54a(4) =55a(5) =63a(6) =66a(7) =67a(8) =68a(9) =69a(10) =70a(11) =72a(12) =74a(13) =75a(14) =76a(15) =77a(16) =79a(17) =80a(18) =82a(19) =83a(20) =84a(21) =86a(22) =87a(23) =88a(24) =90a(25) =91a(26) =93a(27) =94a(28) =95a(29) =96