a(1) = 1; a(n+1) is the smallest number > a(n) which differs from it at every digit.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =5a(5) =6a(6) =7a(7) =8a(8) =9a(9) =10a(10) =21a(11) =30a(12) =41a(13) =50a(14) =61a(15) =70a(16) =81a(17) =90a(18) =101a(19) =210a(20) =301a(21) =410a(22) =501a(23) =610a(24) =701a(25) =810a(26) =901a(27) =1010a(28) =2101a(29) =3010