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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 4176 |
| 8 | 26140 |
| 9 | 185084 |
| 10 | 1491098 |
| 11 | 13285034 |
| 12 | 132514356 |
| 13 | 1321161252 |
| 14 | 14181339764 |
| 15 | 164574628260 |
| 16 | 2057033314380 |
[1,2,6,24,120,720,4176,26140,185084,1491098, 13285034,132514356,1321161252,14181339764, 164574628260,2057033314380] |