# A107762 (b-file synthesized from sequence entry) 1 1 2 2 3 6 4 24 5 60 6 432 7 3360 8 6912 9 86400 10 1080000 11 3432000 12 57542400 13 601810560 14 3374784000 15 71391196800 16 1506917744640 17 8134703216640 18 87731370397440 19 2330058011258880 20 15991083879321600 21 484342868413071360