Largest number whose square has n digits.

Terms

a(0) =3a(1) =9a(2) =31a(3) =99a(4) =316a(5) =999a(6) =3162a(7) =9999a(8) =31622a(9) =99999a(10) =316227a(11) =999999a(12) =3162277a(13) =9999999a(14) =31622776a(15) =99999999a(16) =316227766a(17) =999999999a(18) =3162277660a(19) =9999999999a(20) =31622776601a(21) =99999999999a(22) =316227766016a(23) =999999999999