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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 18 |
| 5 | 107 |
| 6 | 1008 |
| 7 | 13113 |
| 8 | 214238 |
| 9 | 4182487 |
| 10 | 94747196 |
| 11 | 2440784645 |
| 12 | 70431957258 |
| 13 | 2249856084803 |
| 14 | 78802876705608 |
| 15 | 3002702793753489 |
| 16 | 123649410977736950 |
| 17 | 5471808106109912815 |
| 18 | 258948617502187143188 |
| 19 | 13049542794706527317597 |
| 20 | 697673361673877090147490 |
[1,2,5,18,107,1008,13113,214238,4182487,94747196, 2440784645,70431957258,2249856084803, 78802876705608,3002702793753489, 123649410977736950,5471808106109912815, 258948617502187143188,13049542794706527317597, 697673361673877090147490] |