Number of forests of ordered trees on n total nodes.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =26a(6) =77a(7) =235a(8) =758a(9) =2504a(10) =8483a(11) =29203a(12) =102030a(13) =360442a(14) =1285926a(15) =4625102a(16) =16754302a(17) =61067430a(18) =223803775a(19) =824188993a(20) =3048383517a(21) =11318928477a(22) =42176798315a(23) =157664823501a(24) =591109863049