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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 23 |
| 5 | 71 |
| 6 | 251 |
| 7 | 883 |
| 8 | 3305 |
| 9 | 12505 |
| 10 | 48895 |
| 11 | 193755 |
| 12 | 783355 |
| 13 | 3205931 |
| 14 | 13302329 |
| 15 | 55764413 |
| 16 | 236174933 |
| 17 | 1008773269 |
| 18 | 4343533967 |
| 19 | 18834033443 |
| 20 | 82201462251 |
| 21 | 360883031291 |
| 22 | 1592993944723 |
| 23 | 7066748314147 |
| 24 | 31493800133173 |
| 25 | 140953938878821 |
| 26 | 633354801073571 |
[1,1,3,7,23,71,251,883,3305,12505,48895,193755, 783355,3205931,13302329,55764413,236174933, 1008773269,4343533967,18834033443,82201462251, 360883031291,1592993944723,7066748314147, 31493800133173,140953938878821,633354801073571] |