n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 18 |
4 | 124 |
5 | 950 |
6 | 8688 |
7 | 89600 |
8 | 1038392 |
9 | 13309272 |
10 | 186471480 |
11 | 2837173152 |
12 | 46466835072 |
13 | 815532508440 |
14 | 15246845864040 |
15 | 302533865599800 |
16 | 6344720827608384 |
17 | 140208886623418752 |
18 | 3254819745378435264 |
19 | 79172189409906466560 |
20 | 2013138139856523598080 |
[1,1,4,18,124,950,8688,89600,1038392,13309272, 186471480,2837173152,46466835072,815532508440, 15246845864040,302533865599800,6344720827608384, 140208886623418752,3254819745378435264, 79172189409906466560,2013138139856523598080] |