Number of polyominoes of site-perimeter n with 8-holes allowed.

Terms

a(0) =1a(1) =0a(2) =2a(3) =4a(4) =12a(5) =32a(6) =110a(7) =340a(8) =1209a(9) =4272a(10) =16166a(11) =61848a(12) =246660a(13) =1004883a(14) =4209124a(15) =18020832a(16) =78898047a(17) =352437205a(18) =1605225878a(19) =7445515638a(20) =35142033027a(21) =168644213617a(22) =822311934788