Number of polyominoes with n cells, symmetric about diagonal 2.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =1a(7) =1a(8) =0a(9) =1a(10) =2a(11) =3a(12) =3a(13) =5a(14) =6a(15) =14a(16) =9a(17) =20a(18) =20a(19) =56a(20) =32a(21) =80a(22) =64a(23) =224a(24) =114a(25) =315a(26) =217a(27) =863a(28) =397a(29) =1234