Number of n-celled polyominoes with exactly 2 holes.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =0a(8) =0a(9) =0a(10) =4a(11) =41a(12) =346a(13) =2384a(14) =14560a(15) =81863a(16) =433172a(17) =2192752a(18) =10726252a(19) =51094203a(20) =238259280a(21) =1092053068a(22) =4934652298a(23) =22034767837a(24) =97407519119a(25) =426916828181