Numbers k such that 8 and 9 occur juxtaposed in the base-10 representation of k but not of k+1.

Terms

a(0) =89a(1) =98a(2) =189a(3) =198a(4) =289a(5) =298a(6) =389a(7) =398a(8) =489a(9) =498a(10) =589a(11) =598a(12) =689a(13) =698a(14) =789a(15) =798a(16) =899a(17) =989a(18) =998a(19) =1089a(20) =1098a(21) =1189a(22) =1198a(23) =1289a(24) =1298a(25) =1389a(26) =1398a(27) =1489a(28) =1498a(29) =1589