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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 37 |
| 4 | 724 |
| 5 | 20209 |
| 6 | 1905630 |
| 7 | 191250531 |
| 8 | 57659285287 |
| 9 | 20931112851787 |
| 10 | 17697850924585423 |
| 11 | 17720783665888137843 |
| 12 | 44421728434157120665320 |
| 13 | 117208746422032553556330253 |
| 14 | 679595843556865572365153402674 |
| 15 | 4907378683411420479410336076467628 |
[1,2,6,37,724,20209,1905630,191250531,57659285287, 20931112851787,17697850924585423, 17720783665888137843,44421728434157120665320, 117208746422032553556330253, 679595843556865572365153402674, 4907378683411420479410336076467628] |