Number of enriched r-trees of size n.

Terms

a(0) =1a(1) =2a(2) =3a(3) =8a(4) =23a(5) =77a(6) =254a(7) =921a(8) =3249a(9) =12133a(10) =44937a(11) =172329a(12) =654895a(13) =2565963a(14) =9956885a(15) =39536964a(16) =156047622a(17) =626262315a(18) =2499486155a(19) =10129445626a(20) =40810378668a(21) =166475139700a(22) =676304156461