Square numbers that remain square when their most-significant (or leftmost) digit is removed.

Terms

a(0) =1a(1) =4a(2) =9a(3) =49a(4) =64a(5) =81a(6) =100a(7) =225a(8) =400a(9) =625a(10) =900a(11) =1225a(12) =2025a(13) =3025a(14) =4225a(15) =4900a(16) =5625a(17) =6400a(18) =7225a(19) =8100a(20) =9025a(21) =10000a(22) =15625a(23) =22500a(24) =27225a(25) =30625a(26) =34225a(27) =40000a(28) =42025a(29) =50625