C_{0} = 1 C_{1} = 1 C_{2} = 2 C_{3} = 5 C_{4} = 14 C_{5} = 42 C_{6} = 132 C_{7} = 429 C_{8} = 1430 C_{9} = 4862 C_{10} = 16796 C_{11} = 58786 C_{12} = 208012 C_{13} = 742900 C_{14} = 2674440 C_{15} = 9694845 C_{16} = 35357670 C_{17} = 129644790 C_{18} = 477638700 C_{19} = 1767263190 C_{20} = 6564120420