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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 8 |
| 5 | 76 |
| 6 | 1452 |
| 7 | 45612 |
| 8 | 2095992 |
| 9 | 131601136 |
| 10 | 10790109464 |
| 11 | 1117867502280 |
| 12 | 142679360514256 |
| 13 | 21987281765799840 |
| 14 | 4023859534010994768 |
| 15 | 862536439626951197192 |
| 16 | 214034590216271750690880 |
| 17 | 60867125826968771742513120 |
| 18 | 19663683837171331703090010864 |
[1,1,2,8,76,1452,45612,2095992,131601136, 10790109464,1117867502280,142679360514256, 21987281765799840,4023859534010994768, 862536439626951197192,214034590216271750690880, 60867125826968771742513120, 19663683837171331703090010864] |