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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 180 |
| 8 | 9132 |
| 9 | 268980 |
| 10 | 6010220 |
| 11 | 112868844 |
| 12 | 1877530740 |
| 13 | 28540603884 |
| 14 | 404562365316 |
| 15 | 5422718644920 |
| 16 | 69428442576136 |
| 17 | 855504181649448 |
| 18 | 10204459810035768 |
| 19 | 118364711625485256 |
| 20 | 1340006035830921720 |
| 21 | 14850353930248138104 |
| 22 | 161502853638370415864 |
| 23 | 1727146533728893094604 |
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