Numbers k such that k and k^2 use only the digits 2, 4, 6, 7 and 8.

Terms

a(0) =2a(1) =8a(2) =22a(3) =26a(4) =28a(5) =68a(6) =82a(7) =88a(8) =262a(9) =278a(10) =472a(11) =474a(12) =478a(13) =668a(14) =826a(15) =2622a(16) =2762a(17) =2878a(18) =4762a(19) =6668a(20) =8762a(21) =8768a(22) =8822a(23) =8874a(24) =26878a(25) =27826a(26) =28678a(27) =66668a(28) =66878a(29) =68474