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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 57 |
| 4 | 166 |
| 5 | 5561 |
| 6 | 16242 |
| 7 | 544897 |
| 8 | 1591526 |
| 9 | 53394321 |
| 10 | 155953282 |
| 11 | 5232098537 |
| 12 | 15281830086 |
| 13 | 512692262281 |
| 14 | 1497463395122 |
| 15 | 50238609604977 |
| 16 | 146736130891846 |
| 17 | 4922871049025441 |
| 18 | 14378643364005762 |
| 19 | 482391124194888217 |
| 20 | 1408960313541672806 |
| 21 | 47269407300050019801 |
[1,2,57,166,5561,16242,544897,1591526,53394321, 155953282,5232098537,15281830086,512692262281, 1497463395122,50238609604977,146736130891846, 4922871049025441,14378643364005762, 482391124194888217,1408960313541672806, 47269407300050019801] |