# A333690 (b-file synthesized from sequence entry) 1 1 2 2 3 3 4 4 5 20 6 48 7 112 8 864 9 2916 10 34560 11 152064 12 1728000 13 9360000 14 108864000 15 1049760000 16 10668672000 17 172802851200 18 2184944025600 19 32025036718080 20 438839318937600 21 6636767477760000 22 108637562880000000 23 1940004332259840000 24 24494663395141632000 25 673031429554176000000