If d,e are consecutive digits of n in base 9, then |d-e|>=4.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =5a(5) =6a(6) =7a(7) =8a(8) =14a(9) =15a(10) =16a(11) =17a(12) =24a(13) =25a(14) =26a(15) =34a(16) =35a(17) =36a(18) =44a(19) =45a(20) =46a(21) =54a(22) =55a(23) =56a(24) =63a(25) =64a(26) =65a(27) =66a(28) =72a(29) =73