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

Terms

a(0) =0a(1) =2a(2) =20a(3) =200a(4) =2000a(5) =20000a(6) =20602a(7) =200000a(8) =206020a(9) =2000000a(10) =2006002a(11) =2060200a(12) =20000000a(13) =20060020a(14) =20602000a(15) =200000000a(16) =200060002a(17) =200600200a(18) =206020000a(19) =2000000000a(20) =2000600020a(21) =2006002000a(22) =2060200000a(23) =20000000000a(24) =20000600002a(25) =20006000200a(26) =20060020000a(27) =20602000000a(28) =200000000000a(29) =200006000020