Largest palindromic substring in 3^n.

Terms

a(0) =1a(1) =3a(2) =9a(3) =7a(4) =8a(5) =4a(6) =9a(7) =8a(8) =656a(9) =9a(10) =9a(11) =1771a(12) =1441a(13) =323a(14) =969a(15) =434a(16) =7a(17) =9a(18) =9a(19) =162261a(20) =44a(21) =353a(22) =313a(23) =414a(24) =282a(25) =88a(26) =828a(27) =484a(28) =767a(29) =3773