# A141052 (b-file synthesized from sequence entry) 2 1 3 4 4 21 5 130 6 930 7 7560 8 68880 9 695520 10 7711200 11 93139200 12 1217462400 13 17124307200 14 257902444800 15 4140968832000 16 70614415872000 17 1274546617344000 18 24275666967552000 19 486580401635328000 20 10238462617743360000 21 225651661258383360000 22 5198503365971435520000