Numbers with the property that all pairs of consecutive base-9 digits differ by 0 or 1.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =5a(5) =6a(6) =7a(7) =8a(8) =9a(9) =10a(10) =11a(11) =19a(12) =20a(13) =21a(14) =29a(15) =30a(16) =31a(17) =39a(18) =40a(19) =41a(20) =49a(21) =50a(22) =51a(23) =59a(24) =60a(25) =61a(26) =69a(27) =70a(28) =71a(29) =79