# A204550 (b-file synthesized from sequence entry)
1 0
2 1
3 1
4 2
5 4
6 20
7 72
8 288
9 864
10 6624
11 35424
12 212544
13 1088640
14 10056960
15 75064320
16 600514560
17 4147200000
18 46664294400
19 440681472000
20 4406814720000
21 39103948800000
22 515545067520000