Metadromes: digits in base 7 are in strict ascending order.

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =4a(5) =5a(6) =6a(7) =9a(8) =10a(9) =11a(10) =12a(11) =13a(12) =17a(13) =18a(14) =19a(15) =20a(16) =25a(17) =26a(18) =27a(19) =33a(20) =34a(21) =41a(22) =66a(23) =67a(24) =68a(25) =69a(26) =74a(27) =75a(28) =76a(29) =82