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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 26 |
| 5 | 152 |
| 6 | 1202 |
| 7 | 12840 |
| 8 | 184060 |
| 9 | 3552960 |
| 10 | 92338448 |
| 11 | 3237738008 |
| 12 | 153574021372 |
| 13 | 9872941474544 |
| 14 | 862850471831896 |
| 15 | 102720981260693424 |
| 16 | 16701084112350547436 |
| 17 | 3715705202756433837504 |
| 18 | 1133547354784950481434016 |
[1,1,2,6,26,152,1202,12840,184060,3552960, 92338448,3237738008,153574021372,9872941474544, 862850471831896,102720981260693424, 16701084112350547436,3715705202756433837504, 1133547354784950481434016] |