Number of forests of rooted trees containing n nodes not counting the root nodes.

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =19a(5) =47a(6) =127a(7) =330a(8) =889a(9) =2378a(10) =6450a(11) =17510a(12) =47907a(13) =131388a(14) =362081a(15) =1000665a(16) =2774857a(17) =7714695a(18) =21505455a(19) =60084062a(20) =168234804a(21) =471977022a(22) =1326558625a(23) =3734804268a(24) =10531738149a(25) =29742332548a(26) =84111212892a(27) =238176473946a(28) =675269414372