Numbers k such that k and k^2 use only the digits 0, 4, 6, 8 and 9.

Terms

a(0) =0a(1) =8a(2) =64a(3) =80a(4) =98a(5) =640a(6) =664a(7) =800a(8) =898a(9) =980a(10) =998a(11) =6400a(12) =6640a(13) =6664a(14) =8000a(15) =8980a(16) =8998a(17) =9800a(18) =9980a(19) =9998a(20) =64000a(21) =66400a(22) =66640a(23) =66664a(24) =80000a(25) =89800a(26) =89980a(27) =89998a(28) =98000a(29) =98998