Numbers k such that k and k^2 use only the digits 0, 1, 3, 4 and 7.

Terms

a(0) =0a(1) =1a(2) =10a(3) =100a(4) =1000a(5) =1071a(6) =10000a(7) =10710a(8) =100000a(9) =107100a(10) =174071a(11) =370771a(12) =1000000a(13) =1071000a(14) =1170771a(15) =1740710a(16) =1743771a(17) =3707710a(18) =10000000a(19) =10710000a(20) =11707710a(21) =17334071a(22) =17407100a(23) =17437710a(24) =37077100a(25) =100000000a(26) =100370001a(27) =107100000a(28) =117077100a(29) =133310701