n | a(n) |
---|---|
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 |
[0,1,1,2,4,20,72,288,864,6624,35424,212544, 1088640,10056960,75064320,600514560,4147200000, 46664294400,440681472000,4406814720000, 39103948800000,515545067520000] |