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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 16 |
| 5 | 74 |
| 6 | 448 |
| 7 | 2418 |
| 8 | 13656 |
| 9 | 106120 |
| 10 | 788328 |
| 11 | 7615458 |
| 12 | 68903424 |
| 13 | 654009926 |
| 14 | 7602830768 |
| 15 | 82353986258 |
| 16 | 1125428610408 |
[1,2,6,16,74,448,2418,13656,106120,788328,7615458, 68903424,654009926,7602830768,82353986258, 1125428610408] |