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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 6 |
| 3 | 30 |
| 4 | 126 |
| 5 | 8190 |
| 6 | 131070 |
| 7 | 524286 |
| 8 | 2147483646 |
| 9 | 2305843009213693950 |
| 10 | 618970019642690137449562110 |
| 11 | 162259276829213363391578010288126 |
| 12 | 170141183460469231731687303715884105726 |
[2,6,30,126,8190,131070,524286,2147483646, 2305843009213693950,618970019642690137449562110, 162259276829213363391578010288126, 170141183460469231731687303715884105726] |