Numbers k such that k and k^2 use only the digits 0, 1, 6, 8 and 9.

Terms

a(0) =0a(1) =1a(2) =9a(3) =10a(4) =90a(5) =99a(6) =100a(7) =109a(8) =900a(9) =901a(10) =990a(11) =999a(12) =1000a(13) =1009a(14) =1090a(15) =9000a(16) =9001a(17) =9010a(18) =9900a(19) =9990a(20) =9999a(21) =10000a(22) =10009a(23) =10090a(24) =10099a(25) =10801a(26) =10900a(27) =81619a(28) =90000a(29) =90001