Numbers k such that k and k^2 use only the digits 4, 5, 6, 7 and 9.

Terms

a(0) =7a(1) =74a(2) =76a(3) =676a(4) =67657a(5) =74476a(6) =97764a(7) =746657a(8) =759576a(9) =774576a(10) =974474a(11) =6674576a(12) =7469657a(13) =7549474a(14) =7745676a(15) =9974766a(16) =67597764a(17) =67797976a(18) =74474476a(19) =74495476a(20) =74669657a(21) =74697764a(22) =74799576a(23) =75475676a(24) =77457574a(25) =97967574a(26) =99777976a(27) =666745676a(28) =675647576a(29) =744759657