Number of branches in all ordered trees with n edges.

Terms

a(0) =1a(1) =3a(2) =11a(3) =41a(4) =154a(5) =582a(6) =2211a(7) =8437a(8) =32318a(9) =124202a(10) =478686a(11) =1849498a(12) =7161556a(13) =27784460a(14) =107980515a(15) =420300045a(16) =1638238710a(17) =6393535170a(18) =24980504010a(19) =97704407790a(20) =382509199020