n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 30 |
4 | 340 |
5 | 5180 |
6 | 99360 |
7 | 2300830 |
8 | 62473600 |
9 | 1946941920 |
10 | 68507714800 |
11 | 2686816932800 |
12 | 116225776497600 |
13 | 5497681373384200 |
14 | 282305750023897600 |
15 | 15640212734095950000 |
16 | 929908726447266966400 |
17 | 59061538103044360083200 |
18 | 3990922849835432102592000 |
[1,1,4,30,340,5180,99360,2300830,62473600, 1946941920,68507714800,2686816932800, 116225776497600,5497681373384200, 282305750023897600,15640212734095950000, 929908726447266966400,59061538103044360083200, 3990922849835432102592000] |