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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 7 |
| 4 | 50 |
| 5 | 475 |
| 6 | 7758 |
| 7 | 232920 |
| 8 | 10474252 |
| 9 | 800434581 |
| 10 | 103737269018 |
| 11 | 21673922882462 |
| 12 | 7564482881717686 |
| 13 | 4386514307465653148 |
[1,1,7,50,475,7758,232920,10474252,800434581, 103737269018,21673922882462,7564482881717686, 4386514307465653148] |