Numbers k such that 2^k does not contain the digit 4 (probably finite).

Terms

a(0) =0a(1) =1a(2) =3a(3) =4a(4) =5a(5) =7a(6) =8a(7) =9a(8) =13a(9) =15a(10) =16a(11) =17a(12) =21a(13) =23a(14) =24a(15) =29a(16) =40a(17) =41a(18) =43a(19) =55a(20) =69a(21) =75a(22) =85a(23) =107