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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 15 |
| 4 | 112 |
| 5 | 1225 |
| 6 | 16896 |
| 7 | 283759 |
| 8 | 5623808 |
| 9 | 128431377 |
| 10 | 3321026560 |
| 11 | 95915951791 |
| 12 | 3060250165248 |
| 13 | 106896447626137 |
| 14 | 4057412577591296 |
| 15 | 166284754020913935 |
| 16 | 7318183421113532416 |
| 17 | 344228133020323687201 |
| 18 | 17233838271273426223104 |
| 19 | 915000759922243030582735 |
[0,1,2,15,112,1225,16896,283759,5623808,128431377, 3321026560,95915951791,3060250165248, 106896447626137,4057412577591296, 166284754020913935,7318183421113532416, 344228133020323687201,17233838271273426223104, 915000759922243030582735] |