# A001801 (b-file synthesized from sequence entry) 0 3 1 15 2 105 3 315 4 6930 5 18018 6 90090 7 218790 8 2078505 9 4849845 10 22309287 11 50702925 12 1825305300 13 4071834900 14 18032411700 15 39671305740 16 347123925225 17 755505013725 18 3273855059475 19 7064634602025 20 121511715154830