Numbers k such that k and k^2 use only the digits 0, 2, 4, 7 and 8.

Terms

a(0) =0a(1) =2a(2) =20a(3) =22a(4) =28a(5) =88a(6) =200a(7) =202a(8) =220a(9) =278a(10) =280a(11) =448a(12) =472a(13) =478a(14) =878a(15) =880a(16) =2000a(17) =2002a(18) =2020a(19) =2022a(20) =2200a(21) =2202a(22) =2780a(23) =2800a(24) =2878a(25) =4480a(26) =4720a(27) =4780a(28) =8780a(29) =8800