Squares with digits 1, 4, 9.

Terms

a(0) =1a(1) =4a(2) =9a(3) =49a(4) =144a(5) =441a(6) =1444a(7) =11449a(8) =44944a(9) =991494144a(10) =4914991449a(11) =149991994944