Number of endofunctions on n labeled points constructed from k rooted trees.

Terms

a(0) =1a(1) =2a(2) =2a(3) =9a(4) =12a(5) =6a(6) =64a(7) =96a(8) =72a(9) =24a(10) =625a(11) =1000a(12) =900a(13) =480a(14) =120a(15) =7776a(16) =12960a(17) =12960a(18) =8640a(19) =3600a(20) =720a(21) =117649a(22) =201684a(23) =216090a(24) =164640a(25) =88200a(26) =30240a(27) =5040a(28) =2097152a(29) =3670016