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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 42 |
| 4 | 326 |
| 5 | 2706 |
| 6 | 23526 |
| 7 | 211546 |
| 8 | 1951494 |
| 9 | 18366882 |
| 10 | 175674054 |
| 11 | 1702686090 |
| 12 | 16686795846 |
| 13 | 165079509042 |
| 14 | 1646340228006 |
| 15 | 16534463822010 |
| 16 | 167081444125702 |
| 17 | 1697551974416706 |
| 18 | 17330661859937670 |
| 19 | 177699201786231530 |
[1,1,6,42,326,2706,23526,211546,1951494,18366882, 175674054,1702686090,16686795846,165079509042, 1646340228006,16534463822010,167081444125702, 1697551974416706,17330661859937670, 177699201786231530] |