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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 42 |
| 4 | 386 |
| 5 | 4944 |
| 6 | 82160 |
| 7 | 1683218 |
| 8 | 40999516 |
| 9 | 1156626990 |
| 10 | 37060382822 |
| 11 | 1328700402564 |
| 12 | 52676695500313 |
| 13 | 2287415069586304 |
| 14 | 107943308165833912 |
| 15 | 5499354613856855290 |
| 16 | 300788453960472434648 |
| 17 | 17577197510240126035698 |
| 18 | 1092833166733915284972350 |
[1,2,7,42,386,4944,82160,1683218,40999516, 1156626990,37060382822,1328700402564, 52676695500313,2287415069586304, 107943308165833912,5499354613856855290, 300788453960472434648,17577197510240126035698, 1092833166733915284972350] |