Number of row-convex polyplets with n cells.

Terms

a(0) =1a(1) =4a(2) =18a(3) =83a(4) =385a(5) =1788a(6) =8305a(7) =38575a(8) =179170a(9) =832189a(10) =3865253a(11) =17952864a(12) =83385309a(13) =387298083a(14) =1798875698a(15) =8355202169a(16) =38807241321a(17) =180247221864a(18) =837190686169