Array read by diagonals downwards: A(n,k) for n>=2 and k>=0 is the number of (n,k)-polyominoes.

Terms

a(0) =1a(1) =2a(2) =2a(3) =2a(4) =4a(5) =5a(6) =3a(7) =11a(8) =20a(9) =12a(10) =3a(11) =17a(12) =60a(13) =68a(14) =35a(15) =4a(16) =32a(17) =151a(18) =302a(19) =289a(20) =108a(21) =4a(22) =45a(23) =322a(24) =955a(25) =1523a(26) =1151a(27) =369a(28) =5a(29) =71