Boustrophedon transform of powers of 2.

Terms

a(0) =1a(1) =3a(2) =9a(3) =28a(4) =93a(5) =338a(6) =1369a(7) =6238a(8) =31993a(9) =183618a(10) =1169229a(11) =8187598a(12) =62545893a(13) =517622498a(14) =4613366689a(15) =44054301358a(16) =448733127793