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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 1 |
| 8 | 84 |
| 9 | 3990 |
| 10 | 141120 |
| 11 | 4138827 |
| 12 | 106469748 |
| 13 | 2484848080 |
| 14 | 53791898160 |
| 15 | 1096912870053 |
| 16 | 21307466872692 |
| 17 | 397605494092170 |
| 18 | 7173885616672320 |
| 19 | 125794299357058879 |
| 20 | 2152559266567924116 |
| 21 | 36065247772657686660 |
| 22 | 593280221500152370800 |
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