Number of trees in all forests of (unlabeled) rooted identity trees with n vertices.

Terms

a(0) =0a(1) =1a(2) =1a(3) =3a(4) =4a(5) =9a(6) =19a(7) =40a(8) =84a(9) =186a(10) =413a(11) =922a(12) =2082a(13) =4733a(14) =10831a(15) =24928a(16) =57648a(17) =133923a(18) =312393a(19) =731328a(20) =1717784a(21) =4047111a(22) =9561517a(23) =22647521a(24) =53770164a(25) =127941813a(26) =305046676a(27) =728688803a(28) =1743752229a(29) =4179697971