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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 61 |
| 5 | 307 |
| 6 | 1845 |
| 7 | 12917 |
| 8 | 103339 |
| 9 | 930059 |
| 10 | 9300596 |
| 11 | 102306556 |
| 12 | 1227678673 |
| 13 | 15959822761 |
| 14 | 223437518655 |
| 15 | 3351562779829 |
| 16 | 53625004477268 |
| 17 | 911625076113560 |
| 18 | 16409251370044092 |
| 19 | 311775776030837765 |
| 20 | 6235515520616755313 |
[2,5,15,61,307,1845,12917,103339,930059,9300596, 102306556,1227678673,15959822761,223437518655, 3351562779829,53625004477268,911625076113560, 16409251370044092,311775776030837765, 6235515520616755313] |