# A033643 (b-file synthesized from sequence entry) 0 1 1 1 2 2 3 6 4 24 5 120 6 24 7 144 8 312 9 1080 10 4632 11 24240 12 9264 13 57744 14 134016 15 517536 16 2338176 17 12725952 18 7014528 19 45192384 20 111428352 21 469862208 22 2213733888 23 12478256064 24 8854935552 25 58767959808 26 152955661824 27 693938824704