Odd-digit perfect powers.

Terms

a(0) =1a(1) =9a(2) =1331a(3) =3375a(4) =35937a(5) =59319a(6) =357911a(7) =753571a(8) =759375a(9) =5177717a(10) =5359375a(11) =5735339a(12) =9393931a(13) =17373979a(14) =37595375a(15) =39135393a(16) =37159393753a(17) =99317171591a(18) =175333911173a(19) =397551775977