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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 18 |
| 4 | 426 |
| 5 | 12040 |
| 6 | 401355 |
| 7 | 15456756 |
| 8 | 676130644 |
| 9 | 33151425840 |
| 10 | 1802216703285 |
| 11 | 107652497473180 |
| 12 | 7012494336544686 |
| 13 | 494963689847333928 |
| 14 | 37648456802884402111 |
| 15 | 3071415347513049808740 |
| 16 | 267644521958509484952360 |
| 17 | 24822151072519637091258976 |
| 18 | 2442314922307988498911793385 |
[1,18,426,12040,401355,15456756,676130644, 33151425840,1802216703285,107652497473180, 7012494336544686,494963689847333928, 37648456802884402111,3071415347513049808740, 267644521958509484952360, 24822151072519637091258976, 2442314922307988498911793385] |