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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 0 |
| 3 | 3 |
| 4 | 24 |
| 5 | 65 |
| 6 | 480 |
| 7 | 8827 |
| 8 | 72576 |
| 9 | 657729 |
| 10 | 13754880 |
| 11 | 215578451 |
| 12 | 2884992000 |
| 13 | 62280478273 |
| 14 | 1404449120256 |
| 15 | 27032417472075 |
| 16 | 640338738708480 |
| 17 | 17729894860794497 |
| 18 | 453894468727209984 |
| 19 | 12438629293065953059 |
[1,1,0,3,24,65,480,8827,72576,657729,13754880, 215578451,2884992000,62280478273,1404449120256, 27032417472075,640338738708480,17729894860794497, 453894468727209984,12438629293065953059] |