Total number of leaves in all rooted ordered trees with n edges.

Terms

a(0) =1a(1) =1a(2) =3a(3) =10a(4) =35a(5) =126a(6) =462a(7) =1716a(8) =6435a(9) =24310a(10) =92378a(11) =352716a(12) =1352078a(13) =5200300a(14) =20058300a(15) =77558760a(16) =300540195a(17) =1166803110a(18) =4537567650a(19) =17672631900a(20) =68923264410a(21) =269128937220