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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 7 |
| 5 | 12 |
| 6 | 56 |
| 7 | 109 |
| 8 | 368 |
| 9 | 1332 |
| 10 | 5656 |
| 11 | 28248 |
| 12 | 140547 |
| 13 | 774325 |
| 14 | 8485151 |
| 15 | 34339452 |
| 16 | 397492132 |
| 17 | 3996973827 |
| 18 | 63229707890 |
| 19 | 1039037824132 |
[0,1,2,3,7,12,56,109,368,1332,5656,28248,140547, 774325,8485151,34339452,397492132,3996973827, 63229707890,1039037824132] |