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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 46 |
| 4 | 544 |
| 5 | 7983 |
| 6 | 144970 |
| 7 | 3097825 |
| 8 | 76494540 |
| 9 | 2139610590 |
| 10 | 66898897827 |
| 11 | 2311748912745 |
| 12 | 87494097274959 |
| 13 | 3599356204576335 |
| 14 | 159917091369687135 |
| 15 | 7631292367127171222 |
| 16 | 389282192196378927707 |
| 17 | 21138914821756778420757 |
| 18 | 1217459545430430305769230 |
[1,1,6,46,544,7983,144970,3097825,76494540, 2139610590,66898897827,2311748912745, 87494097274959,3599356204576335, 159917091369687135,7631292367127171222, 389282192196378927707,21138914821756778420757, 1217459545430430305769230] |