a(n) = Catalan(n)*Motzkin(n-1).

Terms

a(0) =1a(1) =2a(2) =10a(3) =56a(4) =378a(5) =2772a(6) =21879a(7) =181610a(8) =1570426a(9) =14024660a(10) =128623768a(11) =1206053576a(12) =11523121900a(13) =111885197400