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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 180 |
| 3 | 40908 |
| 4 | 43964700 |
| 5 | 232068730044 |
| 6 | 6206909793496236 |
| 7 | 858502190008810133292 |
| 8 | 622342168717398556687064028 |
| 9 | 2386083493285894017930101786679468 |
[4,180,40908,43964700,232068730044, 6206909793496236,858502190008810133292, 622342168717398556687064028, 2386083493285894017930101786679468] |