Numbers k such that k and k^2 use only the digits 0, 2, 4, 5 and 7.

Terms

a(0) =0a(1) =2a(2) =5a(3) =20a(4) =45a(5) =50a(6) =52a(7) =200a(8) =205a(9) =450a(10) =455a(11) =500a(12) =502a(13) =505a(14) =520a(15) =745a(16) =755a(17) =2000a(18) =2005a(19) =2050a(20) =2245a(21) =4500a(22) =4550a(23) =4552a(24) =5000a(25) =5002a(26) =5005a(27) =5020a(28) =5045a(29) =5050