Number of strip poly-IH68-tiles (holes allowed) with n cells.

Terms

a(0) =1a(1) =1a(2) =4a(3) =7a(4) =19a(5) =41a(6) =104a(7) =235a(8) =572a(9) =1331a(10) =3193a(11) =7485a(12) =17811a(13) =41867a(14) =99181a(15) =233157a(16) =550718a(17) =1293817a(18) =3049649a(19) =7158201a(20) =16845217a(21) =39504435a(22) =92842398