Number of one-sided chessboard polyominoes with n cells.

Terms

a(0) =2a(1) =1a(2) =4a(3) =10a(4) =36a(5) =108a(6) =392a(7) =1363a(8) =5000a(9) =18223a(10) =67792a(11) =252938a(12) =952540a(13) =3602478a(14) =13699554a(15) =52296713a(16) =200406388a(17) =770411478a(18) =2970401696a(19) =11482395526a(20) =44491881090a(21) =172766311857a(22) =672186650116