# A173843 (b-file synthesized from sequence entry)
0 1
1 1
2 2
3 6
4 12
5 72
6 336
7 2640
8 17760
9 175680
10 1543680
11 18385920
12 199019520
13 2771112960
14 35611269120
15 567422392320
16 8437755432960
17 151385755852800
18 2556188496691200
19 50989753530777600
20 963558923688345600
21 21152552961009254400
22 442230750973683302400