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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 120 |
| 4 | 2198 |
| 5 | 54304 |
| 6 | 1674468 |
| 7 | 61736880 |
| 8 | 2644978110 |
| 9 | 129019925424 |
| 10 | 7056278570108 |
| 11 | 427516982398576 |
| 12 | 28417031969575260 |
| 13 | 2055803302988520320 |
| 14 | 160786792285272198088 |
| 15 | 13517797622576903566560 |
| 16 | 1215656330296317906395790 |
| 17 | 116440107306323155369822800 |
[1,2,10,120,2198,54304,1674468,61736880, 2644978110,129019925424,7056278570108, 427516982398576,28417031969575260, 2055803302988520320,160786792285272198088, 13517797622576903566560,1215656330296317906395790, 116440107306323155369822800] |