Least difference between 5^n and a power of 2.

Terms

a(0) =0a(1) =1a(2) =7a(3) =3a(4) =113a(5) =971a(6) =759a(7) =12589a(8) =128481a(9) =144027a(10) =1377017a(11) =15273693a(12) =24294831a(13) =146961301a(14) =1808548329a(15) =3842160243a(16) =15148937153a(17) =213183639237a(18) =583349245479