a(n) = smallest n-digit square.

Terms

a(0) =1a(1) =16a(2) =100a(3) =1024a(4) =10000a(5) =100489a(6) =1000000a(7) =10004569a(8) =100000000a(9) =1000014129a(10) =10000000000a(11) =100000147984a(12) =1000000000000