Numbers k such that 2^k does not contain the digit 5 (probably finite).

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =4a(5) =5a(6) =6a(7) =7a(8) =10a(9) =11a(10) =12a(11) =13a(12) =14a(13) =15a(14) =17a(15) =18a(16) =22a(17) =23a(18) =24a(19) =26a(20) =27a(21) =30a(22) =31a(23) =32a(24) =34a(25) =36a(26) =38a(27) =43a(28) =46a(29) =55