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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 3 |
| 6 | 15 |
| 7 | 31 |
| 8 | 119 |
| 9 | 555 |
| 10 | 2138 |
| 11 | 9548 |
| 12 | 33391 |
| 13 | 136682 |
| 14 | 468971 |
| 15 | 1753525 |
| 16 | 5789709 |
| 17 | 19745186 |
| 18 | 63565260 |
| 19 | 203046061 |
| 20 | 638284176 |
| 21 | 1947963410 |
| 22 | 5979604119 |
| 23 | 17725544038 |
| 24 | 53252284414 |
| 25 | 155128241215 |
| 26 | 456635560332 |
| 27 | 1314718658955 |
| 28 | 3796821176997 |
[1,1,1,1,3,15,31,119,555,2138,9548,33391,136682, 468971,1753525,5789709,19745186,63565260, 203046061,638284176,1947963410,5979604119, 17725544038,53252284414,155128241215,456635560332, 1314718658955,3796821176997] |