Number of asymmetric n-ominoes in n-2 space.

Terms

a(0) =0a(1) =1a(2) =4a(3) =13a(4) =42a(5) =113a(6) =309a(7) =792a(8) =2049a(9) =5167a(10) =13071a(11) =32724a(12) =82006a(13) =204619a(14) =510655a(15) =1272101a(16) =3168971a(17) =7888446a(18) =19636642a(19) =48868367a(20) =121621466a(21) =302673515a(22) =753319709a(23) =1875049668a(24) =4667676111a(25) =11620911254a(26) =28936281066a(27) =72062264255