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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 100 |
| 6 | 408 |
| 7 | 1631 |
| 8 | 6440 |
| 9 | 25263 |
| 10 | 98790 |
| 11 | 385803 |
| 12 | 1506156 |
| 13 | 5881057 |
| 14 | 22974406 |
| 15 | 89804910 |
| 16 | 351279584 |
| 17 | 1375035208 |
| 18 | 5386203792 |
| 19 | 21113167346 |
| 20 | 82816267480 |
| 21 | 325055630634 |
| 22 | 1276635121388 |
| 23 | 5016837177052 |
| 24 | 19725798613152 |
| 25 | 77601159558800 |
[1,2,6,24,100,408,1631,6440,25263,98790,385803, 1506156,5881057,22974406,89804910,351279584, 1375035208,5386203792,21113167346,82816267480, 325055630634,1276635121388,5016837177052, 19725798613152,77601159558800] |