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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 18 |
| 4 | 9 |
| 5 | 900 |
| 6 | 450 |
| 7 | 11025 |
| 8 | 11025 |
| 9 | 793800 |
| 10 | 396900 |
| 11 | 48024900 |
| 12 | 12006225 |
| 13 | 8116208100 |
[1,1,1,18,9,900,450,11025,11025,793800,396900, 48024900,12006225,8116208100] |