a(n) = smallest k such that 2k has digit sum = n.

Terms

a(0) =5a(1) =1a(2) =6a(3) =2a(4) =7a(5) =3a(6) =8a(7) =4a(8) =9a(9) =14a(10) =19a(11) =24a(12) =29a(13) =34a(14) =39a(15) =44a(16) =49a(17) =99a(18) =149a(19) =199a(20) =249a(21) =299a(22) =349a(23) =399a(24) =449a(25) =499a(26) =999a(27) =1499a(28) =1999a(29) =2499