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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 32 |
| 5 | 172 |
| 6 | 1038 |
| 7 | 6865 |
| 8 | 49098 |
| 9 | 376942 |
| 10 | 3094812 |
| 11 | 27129690 |
| 12 | 253821716 |
| 13 | 2534600760 |
| 14 | 27012498668 |
| 15 | 307083883519 |
| 16 | 3719224056464 |
| 17 | 47898505899624 |
| 18 | 654343988611350 |
| 19 | 9455986402701388 |
| 20 | 144138413744793426 |
| 21 | 2311030293590097634 |
| 22 | 38871924229882607774 |
[1,1,2,7,32,172,1038,6865,49098,376942,3094812, 27129690,253821716,2534600760,27012498668, 307083883519,3719224056464,47898505899624, 654343988611350,9455986402701388, 144138413744793426,2311030293590097634, 38871924229882607774] |