# A083484 (b-file synthesized from sequence entry) 1 1 2 4 3 12 4 60 5 420 6 2520 7 27720 8 720720 9 720720 10 24504480 11 465585120 12 2793510720 13 64250746560 14 642507465600 15 1927522396800 16 111796299014400 17 3465685269446400 18 20794111616678400 19 727793906583744000