Number of arborescent partitions with exactly n parts.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =19a(6) =44a(7) =96a(8) =220a(9) =489a(10) =1115a(11) =2483a(12) =5646a(13) =12571a(14) =28343a(15) =63152a(16) =141621a(17) =314330a(18) =701327a(19) =1552149a(20) =3445128a(21) =7599990a(22) =16789039a(23) =36908077