n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 2 |
3 | 7 |
4 | 32 |
5 | 180 |
6 | 1210 |
7 | 9520 |
8 | 85680 |
9 | 867160 |
10 | 9749600 |
11 | 120582000 |
12 | 1626994600 |
13 | 23782158400 |
14 | 374367193200 |
15 | 6314037129400 |
16 | 113591474796800 |
17 | 2171267969270400 |
18 | 43944509528920000 |
19 | 938808209417478400 |
20 | 21111813400597920000 |
21 | 498498097342637392000 |
[1,1,2,7,32,180,1210,9520,85680,867160,9749600, 120582000,1626994600,23782158400,374367193200, 6314037129400,113591474796800,2171267969270400, 43944509528920000,938808209417478400, 21111813400597920000,498498097342637392000] |