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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 13 |
| 5 | 67 |
| 6 | 411 |
| 7 | 2921 |
| 8 | 23633 |
| 9 | 214551 |
| 10 | 2160343 |
| 11 | 23897269 |
| 12 | 288102189 |
| 13 | 3760013027 |
| 14 | 52816397219 |
| 15 | 794536751217 |
| 16 | 12744659120521 |
| 17 | 217140271564591 |
| 18 | 3916221952414383 |
| 19 | 74539067188152941 |
| 20 | 1493136645424092773 |
| 21 | 31400620285465593339 |
| 22 | 691708660911435955579 |
[0,1,3,13,67,411,2921,23633,214551,2160343, 23897269,288102189,3760013027,52816397219, 794536751217,12744659120521,217140271564591, 3916221952414383,74539067188152941, 1493136645424092773,31400620285465593339, 691708660911435955579] |