# A131553 (b-file synthesized from sequence entry)
1 2
2 2
3 6
4 8
5 120
6 12
7 5040
8 384
9 12960
10 640
11 39916800
12 1152
13 6227020800
14 80640
15 5443200
16 10321920
17 355687428096000
18 290304
19 121645100408832000
20 38707200
21 384758035200
22 6812467200
23 25852016738884976640000
24 139345920