Number of fixed n-celled polyominoes with 1 hole.

Terms

a(0) =4a(1) =41a(2) =272a(3) =1516a(4) =7688a(5) =36726a(6) =168528a(7) =751742a(8) =3284460a(9) =14127796a(10) =60040812a(11) =252749460a(12) =1055898224a(13) =4383854044a(14) =18107682684a(15) =74474755264a(16) =305200110920