n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 18 |
4 | 120 |
5 | 840 |
6 | 7920 |
7 | 75600 |
8 | 887040 |
9 | 10886400 |
10 | 152409600 |
11 | 2235340800 |
12 | 36883123200 |
13 | 628929100800 |
14 | 11769069312000 |
15 | 230150688768000 |
16 | 4833164464128000 |
17 | 105639166144512000 |
18 | 2464913876705280000 |
19 | 59606099200327680000 |
20 | 1525429559126753280000 |
21 | 40464026199993876480000 |
[1,1,4,18,120,840,7920,75600,887040,10886400, 152409600,2235340800,36883123200,628929100800, 11769069312000,230150688768000,4833164464128000, 105639166144512000,2464913876705280000, 59606099200327680000,1525429559126753280000, 40464026199993876480000] |