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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 6 |
| 3 | 25 |
| 4 | 98 |
| 5 | 1023 |
| 6 | 4095 |
| 7 | 41225 |
| 8 | 169765 |
| 9 | 1698159 |
| 10 | 36519555 |
| 11 | 160645503 |
| 12 | 3231947595 |
| 13 | 30273024983 |
| 14 | 138712176295 |
| 15 | 1310535994367 |
| 16 | 24708300742602 |
| 17 | 445940506273291 |
| 18 | 2153773851389587 |
| 19 | 38488228121936551 |
| 20 | 357912185755244035 |
[2,6,25,98,1023,4095,41225,169765,1698159, 36519555,160645503,3231947595,30273024983, 138712176295,1310535994367,24708300742602, 445940506273291,2153773851389587, 38488228121936551,357912185755244035] |