Numbers k such that the decimal expansion of 2^k contains no 0.

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =4a(5) =5a(6) =6a(7) =7a(8) =8a(9) =9a(10) =13a(11) =14a(12) =15a(13) =16a(14) =18a(15) =19a(16) =24a(17) =25a(18) =27a(19) =28a(20) =31a(21) =32a(22) =33a(23) =34a(24) =35a(25) =36a(26) =37a(27) =39a(28) =49a(29) =51