# A131681 (b-file synthesized from sequence entry)
0 0
1 1
2 8
3 48
4 384
5 1440
6 8640
7 40320
8 184320
9 829440
10 5529600
11 18247680
12 87588864
13 474439680
14 1532805120
15 7664025600
16 32699842560
17 130288435200
18 517321728000
19 2184247296000
20 9196830720000
21 38626689024000
22 188841590784000