Number of n-celled free polyominoes without holes.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =5a(5) =12a(6) =35a(7) =107a(8) =363a(9) =1248a(10) =4460a(11) =16094a(12) =58937a(13) =217117a(14) =805475a(15) =3001127a(16) =11230003a(17) =42161529a(18) =158781106a(19) =599563893a(20) =2269506062a(21) =8609442688a(22) =32725637373a(23) =124621833354a(24) =475368834568