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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 46 |
| 5 | 335 |
| 6 | 2786 |
| 7 | 28357 |
| 8 | 325382 |
| 9 | 4280859 |
| 10 | 62437882 |
| 11 | 1010306825 |
| 12 | 17852477006 |
| 13 | 343275422503 |
| 14 | 7120802805650 |
| 15 | 158697470231757 |
| 16 | 3778977532041430 |
| 17 | 95794295907958547 |
| 18 | 2574920565897373610 |
| 19 | 73164585387874543057 |
| 20 | 2191028450841437523230 |
| 21 | 68974613397532849153311 |
[1,1,2,9,46,335,2786,28357,325382,4280859, 62437882,1010306825,17852477006,343275422503, 7120802805650,158697470231757,3778977532041430, 95794295907958547,2574920565897373610, 73164585387874543057,2191028450841437523230, 68974613397532849153311] |