First differences of A007088.

Terms

a(0) =1a(1) =9a(2) =1a(3) =89a(4) =1a(5) =9a(6) =1a(7) =889a(8) =1a(9) =9a(10) =1a(11) =89a(12) =1a(13) =9a(14) =1a(15) =8889a(16) =1a(17) =9a(18) =1a(19) =89a(20) =1a(21) =9a(22) =1a(23) =889a(24) =1a(25) =9a(26) =1a(27) =89a(28) =1a(29) =9