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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 15 |
| 5 | 102 |
| 6 | 4166 |
| 7 | 402631 |
| 8 | 76374899 |
| 9 | 27231987762 |
| 10 | 18177070202320 |
| 11 | 22801993267433275 |
| 12 | 54212469444212172845 |
| 13 | 246812697326518127351384 |
| 14 | 2173787304796735262709419350 |
| 15 | 37373588848096468764431235680525 |
| 16 | 1263513534110606141026676778422031561 |
[1,1,2,4,15,102,4166,402631,76374899,27231987762, 18177070202320,22801993267433275, 54212469444212172845,246812697326518127351384, 2173787304796735262709419350, 37373588848096468764431235680525, 1263513534110606141026676778422031561] |