Numbers n such that string 9,9 occurs in the base 10 representation of n but not of n+1.

Terms

a(0) =99a(1) =199a(2) =299a(3) =399a(4) =499a(5) =599a(6) =699a(7) =799a(8) =899a(9) =999a(10) =1099a(11) =1199a(12) =1299a(13) =1399a(14) =1499a(15) =1599a(16) =1699a(17) =1799a(18) =1899a(19) =1999a(20) =2099a(21) =2199a(22) =2299a(23) =2399a(24) =2499a(25) =2599a(26) =2699a(27) =2799a(28) =2899a(29) =2999