Numbers having three 9's in base 10.

Terms

a(0) =999a(1) =1999a(2) =2999a(3) =3999a(4) =4999a(5) =5999a(6) =6999a(7) =7999a(8) =8999a(9) =9099a(10) =9199a(11) =9299a(12) =9399a(13) =9499a(14) =9599a(15) =9699a(16) =9799a(17) =9899a(18) =9909a(19) =9919a(20) =9929a(21) =9939a(22) =9949a(23) =9959a(24) =9969a(25) =9979a(26) =9989a(27) =9990a(28) =9991a(29) =9992