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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 27 |
| 4 | 173 |
| 5 | 977 |
| 6 | 5963 |
| 7 | 36569 |
| 8 | 229949 |
| 9 | 1451137 |
| 10 | 9210249 |
| 11 | 58617915 |
| 12 | 374278491 |
| 13 | 2396497371 |
| 14 | 15387074629 |
| 15 | 99039136267 |
| 16 | 638882616201 |
| 17 | 4129364962373 |
| 18 | 26735915952717 |
| 19 | 173368759816541 |
| 20 | 1125743820087835 |
| 21 | 7318831174181965 |
[1,5,27,173,977,5963,36569,229949,1451137,9210249, 58617915,374278491,2396497371,15387074629, 99039136267,638882616201,4129364962373, 26735915952717,173368759816541,1125743820087835, 7318831174181965] |