n | a(n) |
---|---|
0 | 1 |
1 | 4 |
2 | 20 |
3 | 112 |
4 | 680 |
5 | 4384 |
6 | 29536 |
7 | 205440 |
8 | 1462368 |
9 | 10587520 |
10 | 77633920 |
11 | 574845440 |
12 | 4289409280 |
13 | 32206976000 |
14 | 243074083840 |
15 | 1842511532032 |
16 | 14018197145088 |
17 | 106996519311360 |
18 | 818973463721984 |
19 | 6284217844736000 |
20 | 48327723087278080 |
21 | 372397083591557120 |
[1,4,20,112,680,4384,29536,205440,1462368, 10587520,77633920,574845440,4289409280, 32206976000,243074083840,1842511532032, 14018197145088,106996519311360,818973463721984, 6284217844736000,48327723087278080, 372397083591557120] |