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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 15 |
| 4 | 85 |
| 5 | 510 |
| 6 | 4051 |
| 7 | 33130 |
| 8 | 291925 |
| 9 | 2661255 |
| 10 | 25059670 |
| 11 | 241724380 |
| 12 | 2379912355 |
| 13 | 23833198140 |
| 14 | 242173108050 |
| 15 | 2491817151160 |
| 16 | 25921371278805 |
| 17 | 272256630756265 |
| 18 | 2884054952424115 |
| 19 | 30784716141936525 |
| 20 | 330853932861650870 |
| 21 | 3577823885433087690 |
| 22 | 38907658120970944700 |
[1,1,5,15,85,510,4051,33130,291925,2661255, 25059670,241724380,2379912355,23833198140, 242173108050,2491817151160,25921371278805, 272256630756265,2884054952424115, 30784716141936525,330853932861650870, 3577823885433087690,38907658120970944700] |