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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 28 |
| 3 | 170 |
| 4 | 1084 |
| 5 | 7100 |
| 6 | 47152 |
| 7 | 315320 |
| 8 | 2115856 |
| 9 | 14221520 |
| 10 | 95666368 |
| 11 | 643790240 |
| 12 | 4333242304 |
| 13 | 29169037760 |
| 14 | 196359046912 |
| 15 | 1321871638400 |
| 16 | 8898817351936 |
| 17 | 59906997474560 |
| 18 | 403295993003008 |
| 19 | 2715005985589760 |
| 20 | 18277548009831424 |
[1,5,28,170,1084,7100,47152,315320,2115856, 14221520,95666368,643790240,4333242304, 29169037760,196359046912,1321871638400, 8898817351936,59906997474560,403295993003008, 2715005985589760,18277548009831424] |