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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 30 |
| 2 | 645 |
| 3 | 12495 |
| 4 | 235305 |
| 5 | 4452840 |
| 6 | 86070600 |
| 7 | 1713927600 |
| 8 | 35318883600 |
| 9 | 754896542400 |
| 10 | 16751853518400 |
| 11 | 386036370720000 |
| 12 | 9235831629024000 |
| 13 | 229285008336384000 |
| 14 | 5902321642753536000 |
| 15 | 157423965566579712000 |
[1,30,645,12495,235305,4452840,86070600, 1713927600,35318883600,754896542400, 16751853518400,386036370720000,9235831629024000, 229285008336384000,5902321642753536000, 157423965566579712000] |