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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 120 |
| 3 | 210 |
| 4 | 1540 |
| 5 | 3003 |
| 6 | 7140 |
| 7 | 11628 |
| 8 | 24310 |
| 9 | 61218182743304701891431482520 |
[1,120,210,1540,3003,7140,11628,24310, 61218182743304701891431482520] |