Total number of leaves and roots in the planted trees of order n.

Terms

a(0) =0a(1) =2a(2) =2a(3) =5a(4) =12a(5) =31a(6) =78a(7) =208a(8) =549a(9) =1490a(10) =4060a(11) =11205a(12) =31074a(13) =86862a(14) =243796a(15) =687643a(16) =1946184a(17) =5526723a(18) =15736664a(19) =44920308a(20) =128495647a(21) =368274074a(22) =1057275163a(23) =3039990187a(24) =8752947291a(25) =25233737677a(26) =72828925967a(27) =210416568930