Number of n-celled polyominoes with exactly 3 holes.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =0a(8) =0a(9) =0a(10) =0a(11) =0a(12) =0a(13) =3a(14) =69a(15) =798a(16) =7021a(17) =51775a(18) =339958a(19) =2053872a(20) =11665593a(21) =63192945a(22) =329798278a(23) =1670466031a(24) =8256762365a(25) =39992202198a(26) =190431003084a(27) =893726550231