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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 13 |
| 5 | 71 |
| 6 | 470 |
| 7 | 3497 |
| 8 | 29203 |
| 9 | 271500 |
| 10 | 2786711 |
| 11 | 31322803 |
| 12 | 382794114 |
| 13 | 5054810585 |
| 14 | 71735226535 |
| 15 | 1088920362030 |
| 16 | 17607174571553 |
| 17 | 302143065676513 |
| 18 | 5484510055766118 |
| 19 | 104999034898520903 |
| 20 | 2114467256458136473 |
| 21 | 44682676397748896010 |
| 22 | 988663144904696100347 |
[1,1,2,3,13,71,470,3497,29203,271500,2786711, 31322803,382794114,5054810585,71735226535, 1088920362030,17607174571553,302143065676513, 5484510055766118,104999034898520903, 2114467256458136473,44682676397748896010, 988663144904696100347] |