Numbers k such that k and k^2 use only the digits 1, 5, 6, 8 and 9.

Terms

a(0) =1a(1) =9a(2) =81a(3) =816a(4) =959a(5) =8119a(6) =9959a(7) =81186a(8) =81619a(9) =811891a(10) =816186a(11) =816619a(12) =956619a(13) =8185169a(14) =81169669a(15) =81558666a(16) =95685169a(17) =816516186a(18) =956659119a(19) =8116968986a(20) =8118866669a(21) =8161616669a(22) =8166516186a(23) =8166816186a(24) =9566566186a(25) =9568696666a(26) =9585851866a(27) =9955811669a(28) =9995581859a(29) =81188661891