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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 42 |
| 4 | 602 |
| 5 | 15144 |
| 6 | 433252 |
| 7 | 18378580 |
| 8 | 839621092 |
| 9 | 52183667212 |
| 10 | 3404551437592 |
| 11 | 286529186194664 |
| 12 | 24947253698767632 |
| 13 | 2701657928740913416 |
| 14 | 299900819552115769424 |
| 15 | 40316833236311531705440 |
| 16 | 5520994078882300886182032 |
[1,4,42,602,15144,433252,18378580,839621092, 52183667212,3404551437592,286529186194664, 24947253698767632,2701657928740913416, 299900819552115769424,40316833236311531705440, 5520994078882300886182032] |