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| n | a(n) |
|---|---|
| 1 | 15 |
| 2 | 61 |
| 3 | 414 |
| 4 | 2237 |
| 5 | 11395 |
| 6 | 57848 |
| 7 | 283334 |
| 8 | 1322739 |
| 9 | 5913303 |
| 10 | 25562453 |
| 11 | 107535218 |
| 12 | 441227618 |
| 13 | 1766804332 |
| 14 | 6908136010 |
| 15 | 26396854433 |
| 16 | 98669023733 |
| 17 | 361096551789 |
| 18 | 1294776383753 |
| 19 | 4551637594734 |
| 20 | 15696174943041 |
| 21 | 53127052915296 |
[15,61,414,2237,11395,57848,283334,1322739, 5913303,25562453,107535218,441227618,1766804332, 6908136010,26396854433,98669023733,361096551789, 1294776383753,4551637594734,15696174943041, 53127052915296] |