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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 20 |
| 4 | 95 |
| 5 | 432 |
| 6 | 2100 |
| 7 | 10429 |
| 8 | 52990 |
| 9 | 273872 |
| 10 | 1435464 |
| 11 | 7610704 |
| 12 | 40747432 |
| 13 | 219972284 |
| 14 | 1196042952 |
| 15 | 6543872976 |
| 16 | 36000272857 |
| 17 | 199016494848 |
| 18 | 1104987607068 |
| 19 | 6159118520824 |
| 20 | 34451516940832 |
| 21 | 193323839813568 |
| 22 | 1087995843781768 |
| 23 | 6139413903894528 |
| 24 | 34728866786674200 |
| 25 | 196895381265884724 |
[1,1,6,20,95,432,2100,10429,52990,273872,1435464, 7610704,40747432,219972284,1196042952,6543872976, 36000272857,199016494848,1104987607068, 6159118520824,34451516940832,193323839813568, 1087995843781768,6139413903894528, 34728866786674200,196895381265884724] |