# A082569 (b-file synthesized from sequence entry)
1 2
2 3
3 8
4 32
5 160
6 960
7 6720
8 53760
9 483840
10 4838400
11 53222400
12 638668800
13 8302694400
14 116237721600
15 1743565824000
16 27897053184000
17 474249904128000
18 8536498274304000
19 162193467211776000
20 3243869344235520000