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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 16 |
| 5 | 74 |
| 6 | 368 |
| 7 | 1776 |
| 8 | 9208 |
| 9 | 53466 |
| 10 | 314212 |
| 11 | 2134376 |
| 12 | 14852630 |
| 13 | 117199526 |
| 14 | 945570742 |
| 15 | 8407963796 |
| 16 | 76231574308 |
[1,2,6,16,74,368,1776,9208,53466,314212,2134376, 14852630,117199526,945570742,8407963796, 76231574308] |