Largest palindromic substring in 8^n.

Terms

a(0) =1a(1) =8a(2) =6a(3) =5a(4) =9a(5) =8a(6) =262a(7) =9a(8) =777a(9) =77a(10) =737a(11) =858a(12) =767a(13) =888a(14) =111a(15) =888a(16) =767a(17) =99a(18) =9a(19) =8558a(20) =606a(21) =808a(22) =838a(23) =565a(24) =828a(25) =71617a(26) =676a(27) =9229a(28) =3113a(29) =474