Numbers k such that k and k^2 use only the digits 1, 2, 6, 7 and 9.

Terms

a(0) =1a(1) =11a(2) =26a(3) =27a(4) =96a(5) =127a(6) =276a(7) =277a(8) =1296a(9) =1619a(10) =2777a(11) =9627a(12) =12719a(13) =16161a(14) =16176a(15) =16619a(16) =27796a(17) =96296a(18) =126969a(19) =127161a(20) =129119a(21) =161761a(22) =161777a(23) =266777a(24) =267619a(25) =269777a(26) =1269761a(27) =1272777a(28) =1617619a(29) =1617627