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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 27720 |
| 3 | 1272320 |
| 4 | 19707450 |
| 5 | 163430400 |
| 6 | 927305904 |
| 7 | 3995658240 |
| 8 | 14261752680 |
| 9 | 43493359616 |
| 10 | 118805241072 |
| 11 | 292653344256 |
| 12 | 671496501200 |
| 13 | 1430857236480 |
| 14 | 2904257385888 |
| 15 | 5571801102336 |
| 16 | 10326899016378 |
| 17 | 18297213419520 |
[1,0,27720,1272320,19707450,163430400,927305904, 3995658240,14261752680,43493359616,118805241072, 292653344256,671496501200,1430857236480, 2904257385888,5571801102336,10326899016378, 18297213419520] |