Numbers k such that k and k^2 use only the digits 1, 4, 5, 6 and 7.

Terms

a(0) =1a(1) =4a(2) =74a(3) =76a(4) =746a(5) =6454a(6) =6754a(7) =7466a(8) =64476a(9) =67466a(10) =67576a(11) =74476a(12) =74616a(13) =644574a(14) =664166a(15) =667576a(16) =675771a(17) =717466a(18) =751776a(19) =4176776a(20) =6455746a(21) =6746454a(22) =7151616a(23) =7174616a(24) =7467574a(25) =64154154a(26) =64556654a(27) =66461754a(28) =66751454a(29) =67651616