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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 45 |
| 2 | 1980 |
| 3 | 87120 |
| 4 | 3833280 |
| 5 | 168664320 |
| 6 | 7421230080 |
| 7 | 326534123520 |
| 8 | 14367501434880 |
| 9 | 632170063134720 |
| 10 | 27815482777927680 |
| 11 | 1223881242228817920 |
| 12 | 53850774658067988480 |
| 13 | 2369434084954991493120 |
| 14 | 104255099738019625697280 |
| 15 | 4587224388472863530680320 |
[1,45,1980,87120,3833280,168664320,7421230080, 326534123520,14367501434880,632170063134720, 27815482777927680,1223881242228817920, 53850774658067988480,2369434084954991493120, 104255099738019625697280, 4587224388472863530680320] |