Numbers whose set of base 10 digits is {0,7}.

Terms

a(0) =0a(1) =7a(2) =70a(3) =77a(4) =700a(5) =707a(6) =770a(7) =777a(8) =7000a(9) =7007a(10) =7070a(11) =7077a(12) =7700a(13) =7707a(14) =7770a(15) =7777a(16) =70000a(17) =70007a(18) =70070a(19) =70077a(20) =70700a(21) =70707a(22) =70770a(23) =70777a(24) =77000a(25) =77007a(26) =77070a(27) =77077a(28) =77700a(29) =77707