Squares using at most two distinct digits, not ending in 0.

Terms

a(0) =1a(1) =4a(2) =9a(3) =16a(4) =25a(5) =36a(6) =49a(7) =64a(8) =81a(9) =121a(10) =144a(11) =225a(12) =441a(13) =484a(14) =676a(15) =1444a(16) =7744a(17) =11881a(18) =29929a(19) =44944a(20) =55225a(21) =69696a(22) =9696996a(23) =6661661161