a(n) = smallest k such that 5k has a digit sum = n.

Terms

a(0) =2a(1) =4a(2) =6a(3) =8a(4) =1a(5) =3a(6) =5a(7) =7a(8) =9a(9) =11a(10) =13a(11) =15a(12) =17a(13) =19a(14) =39a(15) =59a(16) =79a(17) =99a(18) =119a(19) =139a(20) =159a(21) =179a(22) =199a(23) =399a(24) =599a(25) =799a(26) =999a(27) =1199a(28) =1399a(29) =1599