Numbers k such that k and k^2 use only the digits 0, 1, 4, 5 and 7.

Terms

a(0) =0a(1) =1a(2) =10a(3) =71a(4) =100a(5) =710a(6) =1000a(7) =1071a(8) =7100a(9) =7451a(10) =10000a(11) =10701a(12) =10710a(13) =70751a(14) =71000a(15) =74510a(16) =75501a(17) =100000a(18) =100501a(19) =107010a(20) =107100a(21) =107451a(22) =707510a(23) =710000a(24) =745100a(25) =745501a(26) =755010a(27) =1000000a(28) =1005010a(29) =1007001