Free polyominoes with 2n squares, having reflectional symmetry on axis that coincides with edges.

A234006

Free polyominoes with 2n squares, having reflectional symmetry on axis that coincides with edges.

Terms

    a(0) =1a(1) =2a(2) =4a(3) =11a(4) =35a(5) =114a(6) =392a(7) =1381a(8) =4998a(9) =18292a(10) =67791a(11) =253182a(12) =952527a(13) =3603389a(14) =13699516a(15) =52300071a(16) =200406183a(17) =770424072a(18) =2970400815a(19) =11482442855a(20) =44491876993a(21) =172766491178a(22) =672186631950

External references