n | a(n) |
---|---|
1 | 1 |
2 | 0 |
3 | 0 |
4 | 2 |
5 | 2 |
6 | 4 |
7 | 28 |
8 | 0 |
9 | 20 |
10 | 52 |
11 | 280 |
12 | 1192 |
13 | 5520 |
14 | 20196 |
15 | 115936 |
16 | 701836 |
17 | 4174032 |
18 | 27261284 |
19 | 193428616 |
20 | 1445733328 |
21 | 11133210948 |
[1,0,0,2,2,4,28,0,20,52,280,1192,5520,20196, 115936,701836,4174032,27261284,193428616, 1445733328,11133210948] |