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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 21 |
| 3 | 55 |
| 4 | 377 |
| 5 | 987 |
| 6 | 6765 |
| 7 | 17711 |
| 8 | 121393 |
| 9 | 317811 |
| 10 | 2178309 |
| 11 | 5702887 |
| 12 | 39088169 |
| 13 | 102334155 |
| 14 | 701408733 |
| 15 | 1836311903 |
| 16 | 12586269025 |
| 17 | 32951280099 |
| 18 | 225851433717 |
| 19 | 591286729879 |
| 20 | 4052739537881 |
| 21 | 10610209857723 |
| 22 | 72723460248141 |
| 23 | 190392490709135 |
| 24 | 1304969544928657 |
| 25 | 3416454622906707 |
[3,21,55,377,987,6765,17711,121393,317811,2178309, 5702887,39088169,102334155,701408733,1836311903, 12586269025,32951280099,225851433717,591286729879, 4052739537881,10610209857723,72723460248141, 190392490709135,1304969544928657,3416454622906707] |