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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 121 |
| 6 | 865 |
| 7 | 3529 |
| 8 | 10753 |
| 9 | 27217 |
| 10 | 7318081 |
| 11 | 96720625 |
| 12 | 689990401 |
| 13 | 3508289929 |
| 14 | 14239793569 |
| 15 | 5933573525881 |
| 16 | 114415115802625 |
| 17 | 1165402803391009 |
| 18 | 8298505279241857 |
| 19 | 46355961619888993 |
| 20 | 26167218073714552321 |
| 21 | 663290722580370585625 |
[1,1,1,1,1,121,865,3529,10753,27217,7318081, 96720625,689990401,3508289929,14239793569, 5933573525881,114415115802625,1165402803391009, 8298505279241857,46355961619888993, 26167218073714552321,663290722580370585625] |