Number of fixed directed convex polyominoes with n cells.

Terms

a(0) =1a(1) =2a(2) =5a(3) =13a(4) =33a(5) =82a(6) =200a(7) =481a(8) =1144a(9) =2699a(10) =6329a(11) =14775a(12) =34381a(13) =79819a(14) =185001a(15) =428290a(16) =990716a(17) =2290424a(18) =5293153a(19) =12229209a(20) =28249088a(21) =65246630a(22) =150687282a(23) =347993954a(24) =803620981a(25) =1855754764a(26) =4285319033a(27) =9895581541a(28) =22850547145a(29) =52765494456