Number of n-celled axially symmetric polyominoes without holes.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =2a(5) =6a(6) =9a(7) =23a(8) =37a(9) =87a(10) =138a(11) =313a(12) =510a(13) =1130a(14) =1859a(15) =4070a(16) =6786a(17) =14750a(18) =24811a(19) =53715a(20) =91096a(21) =196769a(22) =335815a(23) =724470a(24) =1243175a(25) =2680212a(26) =4619999a(27) =9957652a(28) =17231447a(29) =37137177