Numbers k such that k and k^2 use only the digits 0, 2, 6, 7 and 8.

Terms

a(0) =0a(1) =26a(2) =260a(3) =826a(4) =2600a(5) =8226a(6) =8260a(7) =26000a(8) =82260a(9) =82600a(10) =260000a(11) =280726a(12) =822600a(13) =826000a(14) =2600000a(15) =2767826a(16) =2807260a(17) =7786026a(18) =8226000a(19) =8260000a(20) =26000000a(21) =27678260a(22) =28072600a(23) =28686026a(24) =77860260a(25) =82260000a(26) =82600000a(27) =88672826a(28) =260000000a(29) =276782600