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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 9 |
| 4 | 64 |
| 5 | 1900 |
| 6 | 5184 |
| 7 | 695310 |
| 8 | 15089664 |
| 9 | 346348629 |
| 10 | 8189440000 |
| 11 | 170553548176 |
| 12 | 4519967588352 |
| 13 | 202522159449675 |
| 14 | 8500218417954816 |
| 15 | 265594041953296875 |
| 16 | 3543051899458551808 |
| 17 | 454740628232312103872 |
| 18 | 5853583711033675481088 |
[0,0,9,64,1900,5184,695310,15089664,346348629, 8189440000,170553548176,4519967588352, 202522159449675,8500218417954816, 265594041953296875,3543051899458551808, 454740628232312103872,5853583711033675481088] |