Numbers k such that k and k^2 use only the digits 0, 1, 4, 6 and 7.

Terms

a(0) =0a(1) =1a(2) =4a(3) =10a(4) =40a(5) =100a(6) =400a(7) =1000a(8) =1071a(9) =4000a(10) =7776a(11) =10000a(12) =10710a(13) =10771a(14) =40000a(15) =77760a(16) =100000a(17) =106771a(18) =106776a(19) =107100a(20) =107710a(21) =400000a(22) =777600a(23) =1000000a(24) =1007046a(25) =1067710a(26) =1067760a(27) =1071000a(28) =1077100a(29) =1077776