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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 18 |
| 5 | 70 |
| 6 | 523 |
| 7 | 4956 |
| 8 | 70926 |
| 9 | 1300201 |
| 10 | 37116376 |
| 11 | 1354115636 |
| 12 | 76887328413 |
| 13 | 5596162598050 |
| 14 | 631149201335604 |
| 15 | 91196507989935319 |
| 16 | 20473605176808584691 |
| 17 | 5885534752273786907540 |
| 18 | 2626715298620574785397735 |
[1,1,5,18,70,523,4956,70926,1300201,37116376, 1354115636,76887328413,5596162598050, 631149201335604,91196507989935319, 20473605176808584691,5885534752273786907540, 2626715298620574785397735] |