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| n | a(n) |
|---|---|
| 1 | 15 |
| 2 | 225 |
| 3 | 2017 |
| 4 | 12467 |
| 5 | 59855 |
| 6 | 240829 |
| 7 | 850875 |
| 8 | 2717731 |
| 9 | 8000608 |
| 10 | 22004896 |
| 11 | 57114321 |
| 12 | 140968221 |
| 13 | 332855049 |
| 14 | 755508149 |
| 15 | 1654943378 |
| 16 | 3509994992 |
| 17 | 7227765020 |
| 18 | 14484196632 |
| 19 | 28304567857 |
| 20 | 54032736159 |
| 21 | 100918573991 |
| 22 | 184671328897 |
[15,225,2017,12467,59855,240829,850875,2717731, 8000608,22004896,57114321,140968221,332855049, 755508149,1654943378,3509994992,7227765020, 14484196632,28304567857,54032736159,100918573991, 184671328897] |