Number of fixed polytans (polyaboloes) with n cells.

Terms

a(0) =4a(1) =9a(2) =24a(3) =71a(4) =224a(5) =740a(6) =2496a(7) =8565a(8) =29792a(9) =104701a(10) =371304a(11) =1326702a(12) =4771380a(13) =17256161a(14) =62712800a(15) =228883359a(16) =838492436a(17) =3081972336a(18) =11361867384a(19) =41998361480a(20) =155620033360a(21) =577900838281