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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 6 |
| 4 | 36 |
| 5 | 510 |
| 6 | 8100 |
| 7 | 158046 |
| 8 | 3679956 |
| 9 | 98048670 |
| 10 | 2968618500 |
| 11 | 100316585886 |
| 12 | 3746574069876 |
| 13 | 153219398980830 |
| 14 | 6809706158264100 |
| 15 | 326828820016946526 |
| 16 | 16846193687562635796 |
| 17 | 928140176998059087390 |
| 18 | 54431376733124465919300 |
| 19 | 3385445099948855523111966 |
[1,0,6,36,510,8100,158046,3679956,98048670, 2968618500,100316585886,3746574069876, 153219398980830,6809706158264100, 326828820016946526,16846193687562635796, 928140176998059087390,54431376733124465919300, 3385445099948855523111966] |