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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 60 |
| 4 | 936 |
| 5 | 21495 |
| 6 | 681480 |
| 7 | 28157451 |
| 8 | 1455590528 |
| 9 | 91689831225 |
| 10 | 6907344210400 |
| 11 | 612700433073707 |
| 12 | 63107430169208832 |
| 13 | 7455570223877314721 |
| 14 | 999839697339310324224 |
| 15 | 150885818035154310155625 |
| 16 | 25434297819615665229168640 |
| 17 | 4758031551536565527014516561 |
[1,1,6,60,936,21495,681480,28157451,1455590528, 91689831225,6907344210400,612700433073707, 63107430169208832,7455570223877314721, 999839697339310324224,150885818035154310155625, 25434297819615665229168640, 4758031551536565527014516561] |