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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 7 |
| 2 | 53 |
| 3 | 347 |
| 4 | 2411 |
| 5 | 16811 |
| 6 | 117659 |
| 7 | 823547 |
| 8 | 5764817 |
| 9 | 40353611 |
| 10 | 282475267 |
| 11 | 1977326753 |
| 12 | 13841287217 |
| 13 | 96889010447 |
| 14 | 678223072853 |
| 15 | 4747561510009 |
| 16 | 33232930569607 |
| 17 | 232630513987231 |
| 18 | 1628413597910497 |
| 19 | 11398895185373167 |
[2,7,53,347,2411,16811,117659,823547,5764817, 40353611,282475267,1977326753,13841287217, 96889010447,678223072853,4747561510009, 33232930569607,232630513987231,1628413597910497, 11398895185373167] |