# A129655 (b-file synthesized from sequence entry) 1 1 2 2 3 6 4 24 5 120 6 720 7 5040 8 55440 9 720720 10 12252240 11 232792560 12 6750984240 13 276790353840 14 12732356276640 15 523410559111440 16 24076885719126240 17 1131613628798933280 18 100713612963105061920 19 20042008979657907322080