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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 19 |
| 5 | 63 |
| 6 | 213 |
| 7 | 729 |
| 8 | 2513 |
| 9 | 8703 |
| 10 | 30232 |
| 11 | 105236 |
| 12 | 366849 |
| 13 | 1280131 |
| 14 | 4470354 |
| 15 | 15619386 |
| 16 | 54595869 |
| 17 | 190891131 |
| 18 | 667590414 |
| 19 | 2335121082 |
| 20 | 8168950665 |
| 21 | 28580354769 |
| 22 | 100000811433 |
| 23 | 349918126509 |
| 24 | 1224476796543 |
| 25 | 4285005630969 |
[1,2,6,19,63,213,729,2513,8703,30232,105236, 366849,1280131,4470354,15619386,54595869, 190891131,667590414,2335121082,8168950665, 28580354769,100000811433,349918126509, 1224476796543,4285005630969] |