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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 22 |
| 5 | 86 |
| 6 | 336 |
| 7 | 1290 |
| 8 | 4870 |
| 9 | 18164 |
| 10 | 67234 |
| 11 | 247786 |
| 12 | 911120 |
| 13 | 3346618 |
| 14 | 12286942 |
| 15 | 45104548 |
| 16 | 165573482 |
| 17 | 607817410 |
| 18 | 2231360192 |
| 19 | 8191763970 |
| 20 | 30074097062 |
| 21 | 110410946820 |
| 22 | 405353571346 |
| 23 | 1488185247962 |
| 24 | 5463619641904 |
| 25 | 20058759689642 |
| 26 | 73642362774478 |
| 27 | 270365534734372 |
[1,2,6,22,86,336,1290,4870,18164,67234,247786, 911120,3346618,12286942,45104548,165573482, 607817410,2231360192,8191763970,30074097062, 110410946820,405353571346,1488185247962, 5463619641904,20058759689642,73642362774478, 270365534734372] |