Number of board-pile polyominoes with n cells.

Terms

a(0) =1a(1) =2a(2) =6a(3) =19a(4) =61a(5) =196a(6) =629a(7) =2017a(8) =6466a(9) =20727a(10) =66441a(11) =212980a(12) =682721a(13) =2188509a(14) =7015418a(15) =22488411a(16) =72088165a(17) =231083620a(18) =740754589a(19) =2374540265a(20) =7611753682a(21) =24400004911a(22) =78215909841a(23) =250726529556a(24) =803721298537