# A228858 (b-file synthesized from sequence entry) 1 6 2 12 3 126 4 60 5 240 6 210 7 1080 8 336 9 1260 10 924 11 2016 12 2640 13 7980 14 6930 15 420 16 2520 17 840 18 3696 19 10080 20 5460 21 3360