a(n)^2 is the smallest square containing exactly n 0's.

Terms

a(0) =0a(1) =10a(2) =320a(3) =100a(4) =3200a(5) =1000a(6) =32000a(7) =10000a(8) =320000a(9) =100000a(10) =3200000a(11) =1000000a(12) =32000000a(13) =10000000a(14) =320000000a(15) =100000000a(16) =3200000000a(17) =1000000000a(18) =32000000000a(19) =10000000000a(20) =320000000000a(21) =100000000000