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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 6 |
| 3 | 14 |
| 4 | 44 |
| 5 | 178 |
| 6 | 892 |
| 7 | 5354 |
| 8 | 37480 |
| 9 | 299842 |
| 10 | 2698580 |
| 11 | 26985802 |
| 12 | 296843824 |
| 13 | 3562125890 |
| 14 | 46307636572 |
| 15 | 648306912010 |
| 16 | 9724603680152 |
| 17 | 155593658882434 |
| 18 | 2645092201001380 |
[1,3,6,14,44,178,892,5354,37480,299842,2698580, 26985802,296843824,3562125890,46307636572, 648306912010,9724603680152,155593658882434, 2645092201001380] |