Smallest number whose sum of digits is 3n+1.

Terms

a(0) =1a(1) =4a(2) =7a(3) =19a(4) =49a(5) =79a(6) =199a(7) =499a(8) =799a(9) =1999a(10) =4999a(11) =7999a(12) =19999a(13) =49999a(14) =79999a(15) =199999a(16) =499999a(17) =799999a(18) =1999999a(19) =4999999a(20) =7999999a(21) =19999999a(22) =49999999a(23) =79999999a(24) =199999999a(25) =499999999a(26) =799999999a(27) =1999999999a(28) =4999999999a(29) =7999999999