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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 9 |
| 5 | 65 |
| 6 | 885 |
| 7 | 20769 |
| 8 | 904799 |
| 9 | 75119535 |
| 10 | 12059144775 |
| 11 | 3777502008115 |
| 12 | 2321770382163177 |
| 13 | 2810098818045932049 |
| 14 | 6714509196242295683053 |
| 15 | 31734155232117923771498025 |
| 16 | 297105206555826680431032956415 |
[0,0,1,3,9,65,885,20769,904799,75119535, 12059144775,3777502008115,2321770382163177, 2810098818045932049,6714509196242295683053, 31734155232117923771498025, 297105206555826680431032956415] |