# A089057 (b-file synthesized from sequence entry) 3 3 4 12 5 60 6 360 7 2520 8 13440 9 120960 10 1209600 11 13305600 12 159667200 13 2075673600 14 29059430400 15 435891456000 16 6974263296000 17 118562476032000 18 2134124568576000 19 40548366802944000 20 810967336058880000