Number of free, holey, treelike polyominoes of n cells.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =1a(7) =5a(8) =32a(9) =144a(10) =662a(11) =2835a(12) =11955a(13) =49083a(14) =199029a(15) =796867a(16) =3163384a(17) =12463807