# A256031 (b-file synthesized from sequence entry) 1 2 2 3 3 12 4 30 5 240 6 840 7 10080 8 45360 9 725760 10 3991680 11 79833600 12 518918400 13 12454041600 14 93405312000 15 2615348736000 16 22230464256000 17 711374856192000 18 6758061133824000 19 243290200817664000 20 2554547108585472000 21 102181884343418880000 22 1175091669949317120000