Numbers k such that k and k^2 use only the digits 1, 4, 6, 7 and 9.

Terms

a(0) =1a(1) =4a(2) =7a(3) =14a(4) =69a(5) =119a(6) =4119a(7) =4446a(8) =4469a(9) =6479a(10) =41469a(11) =44469a(12) =69114a(13) =641619a(14) =679479a(15) =4116974a(16) =4176974a(17) =4179676a(18) =4411479a(19) =6416969a(20) =6477974a(21) =6646614a(22) =6646764a(23) =6691771a(24) =6794446a(25) =9719114a(26) =41766969a(27) =41794676a(28) =41799479a(29) =64169446