# A052743 (b-file synthesized from sequence entry) 0 0 1 1 2 2 3 6 4 48 5 480 6 5040 7 65520 8 1048320 9 18869760 10 377395200 11 8462361600 12 209802700800 13 5666588928000 14 165900288153600 15 5242466541312000 16 177718177308672000 17 6430828699975680000 18 247490157968621568000