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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 6 |
| 2 | 42 |
| 3 | 756 |
| 4 | 35532 |
| 5 | 4370436 |
| 6 | 1407280392 |
| 7 | 1186337370456 |
| 8 | 2618246576596392 |
| 9 | 15128228719573952976 |
| 10 | 228844715840995186667952 |
| 11 | 9062937281450932377610903056 |
| 12 | 939663463215395570775453650652192 |
| 13 | 255065069445576619918001465293982953056 |
[2,6,42,756,35532,4370436,1407280392, 1186337370456,2618246576596392, 15128228719573952976,228844715840995186667952, 9062937281450932377610903056, 939663463215395570775453650652192, 255065069445576619918001465293982953056] |