# A174197 (b-file synthesized from sequence entry) 1 4 2 6 3 24 4 30 5 720 6 168 7 720 8 2520 9 151200 10 55440 11 665280 12 1310400 13 47520 14 454053600 15 2471040 16 3598560 17 4410806400 18 1769644800 19 801964800 20 1150269120 21 2283240960