Numbers k such that k and k^2 use only the digits 1, 4, 5, 7 and 8.

Terms

a(0) =1a(1) =88a(2) =888a(3) =4141a(4) =7471a(5) =7588a(6) =8471a(7) =8878a(8) =418878a(9) =747588a(10) =758141a(11) =4145771a(12) =8478141a(13) =41458141a(14) =41818878a(15) =41855488a(16) =74485888a(17) =718158141a(18) =744411478a(19) =747541141a(20) =878148141a(21) =887574141a(22) =888154141a(23) =4144585478a(24) =7444115471a(25) =8454854141a(26) =8881151478a(27) =74711811488a(28) =75877847588a(29) =84745157471