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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 15 |
| 5 | 134 |
| 6 | 978 |
| 7 | 10370 |
| 8 | 114292 |
| 9 | 2035620 |
| 10 | 29935144 |
| 11 | 567866832 |
| 12 | 14295267600 |
| 13 | 488489391072 |
| 14 | 12470564424960 |
[1,2,4,15,134,978,10370,114292,2035620,29935144, 567866832,14295267600,488489391072,12470564424960] |