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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 6 |
| 4 | 40 |
| 5 | 375 |
| 6 | 5176 |
| 7 | 103236 |
| 8 | 2922445 |
| 9 | 116011230 |
| 10 | 6433447396 |
| 11 | 498234407451 |
| 12 | 54007795331920 |
| 13 | 8213123246906760 |
| 14 | 1756336596363006841 |
| 15 | 528975889250504033526 |
| 16 | 224688018516023267969440 |
| 17 | 134708289561117007261966815 |
[0,1,6,40,375,5176,103236,2922445,116011230, 6433447396,498234407451,54007795331920, 8213123246906760,1756336596363006841, 528975889250504033526,224688018516023267969440, 134708289561117007261966815] |