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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 14 |
| 4 | 204 |
| 5 | 5104 |
| 6 | 195040 |
| 7 | 10570416 |
| 8 | 771171296 |
| 9 | 72871890176 |
| 10 | 8658173200896 |
| 11 | 1263326817241600 |
| 12 | 222078432102900736 |
| 13 | 46291130226003357696 |
| 14 | 11289508838355990634496 |
| 15 | 3184719803676823556888576 |
| 16 | 1028950134725811309304442880 |
| 17 | 377483869192551997938994315264 |
| 18 | 156057810922284533544621710639104 |
[1,2,14,204,5104,195040,10570416,771171296, 72871890176,8658173200896,1263326817241600, 222078432102900736,46291130226003357696, 11289508838355990634496,3184719803676823556888576, 1028950134725811309304442880, 377483869192551997938994315264, 156057810922284533544621710639104] |