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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 28 |
| 5 | 225 |
| 6 | 2274 |
| 7 | 24955 |
| 8 | 286143 |
| 9 | 3367443 |
| 10 | 40358811 |
| 11 | 490598186 |
[1,1,5,28,225,2274,24955,286143,3367443,40358811, 490598186] |