Numbers k such that k and k^2 use only the digits 0, 1, 2, 6 and 7.

Terms

a(0) =0a(1) =1a(2) =10a(3) =11a(4) =26a(5) =100a(6) =101a(7) =110a(8) =260a(9) =276a(10) =776a(11) =1000a(12) =1001a(13) =1010a(14) =1011a(15) =1100a(16) =1101a(17) =2600a(18) =2760a(19) =2776a(20) =7760a(21) =10000a(22) =10001a(23) =10010a(24) =10011a(25) =10100a(26) =10110a(27) =10776a(28) =11000a(29) =11001