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| n | a(n) |
|---|---|
| 0 | -1 |
| 1 | 1 |
| 2 | 9 |
| 3 | 75 |
| 4 | 735 |
| 5 | 8505 |
| 6 | 114345 |
| 7 | 1756755 |
| 8 | 30405375 |
| 9 | 585810225 |
| 10 | 12439852425 |
| 11 | 288735522075 |
| 12 | 7273385294175 |
| 13 | 197646339515625 |
| 14 | 5763367260275625 |
| 15 | 179518217255251875 |
| 16 | 5948862302837829375 |
| 17 | 208977775735174070625 |
| 18 | 7757508341684492015625 |
| 19 | 303429397707601987696875 |
[-1,1,9,75,735,8505,114345,1756755,30405375, 585810225,12439852425,288735522075,7273385294175, 197646339515625,5763367260275625, 179518217255251875,5948862302837829375, 208977775735174070625,7757508341684492015625, 303429397707601987696875] |