Every digit that appears in k also appears at least once in k^2.

Terms

a(0) =0a(1) =1a(2) =5a(3) =6a(4) =10a(5) =11a(6) =25a(7) =27a(8) =50a(9) =55a(10) =60a(11) =63a(12) =64a(13) =66a(14) =74a(15) =76a(16) =95a(17) =96a(18) =99a(19) =100a(20) =101a(21) =105a(22) =110a(23) =111a(24) =112a(25) =115a(26) =116a(27) =125a(28) =139a(29) =142