# A110347 (b-file synthesized from sequence entry) 1 1 2 3 3 24 4 180 5 2520 6 30240 7 604800 8 9979200 9 259459200 10 5448643200 11 174356582400 12 4446092851200 13 168951528345600 14 5068545850368000 15 223016017416192000 16 7694052600858624000 17 384702630042931200000 18 15003402571674316800000