Numbers n such that 2^n does not contain the digit 7.

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =4a(5) =5a(6) =6a(7) =7a(8) =8a(9) =9a(10) =10a(11) =11a(12) =12a(13) =13a(14) =14a(15) =16a(16) =18a(17) =19a(18) =22a(19) =23a(20) =25a(21) =28a(22) =33a(23) =41a(24) =42a(25) =49a(26) =50a(27) =54a(28) =61a(29) =71