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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 27 |
| 5 | 89 |
| 6 | 300 |
| 7 | 1008 |
| 8 | 3563 |
| 9 | 12483 |
| 10 | 44583 |
| 11 | 158600 |
| 12 | 572548 |
| 13 | 2057792 |
| 14 | 7451924 |
| 15 | 26913176 |
| 16 | 98321435 |
| 17 | 358017691 |
| 18 | 1312060393 |
| 19 | 4797471336 |
| 20 | 17666696455 |
| 21 | 64890598361 |
| 22 | 239454075896 |
| 23 | 881886659872 |
| 24 | 3264772507980 |
| 25 | 12061404124676 |
[1,1,3,8,27,89,300,1008,3563,12483,44583,158600, 572548,2057792,7451924,26913176,98321435, 358017691,1312060393,4797471336,17666696455, 64890598361,239454075896,881886659872, 3264772507980,12061404124676] |