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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 26 |
| 4 | 247 |
| 5 | 4643 |
| 6 | 135578 |
| 7 | 7279940 |
| 8 | 684911503 |
| 9 | 111613234643 |
| 10 | 31882671447699 |
| 11 | 15903381470791210 |
| 12 | 13849831552030467450 |
| 13 | 21073883712902398984415 |
[1,7,26,247,4643,135578,7279940,684911503, 111613234643,31882671447699,15903381470791210, 13849831552030467450,21073883712902398984415] |