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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 16 |
| 4 | 148 |
| 5 | 2400 |
| 6 | 62800 |
| 7 | 2150784 |
| 8 | 89051520 |
| 9 | 4376959488 |
| 10 | 264110948352 |
[1,3,16,148,2400,62800,2150784,89051520, 4376959488,264110948352] |