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| n | a(n) |
|---|---|
| 2 | 2 |
| 3 | 21 |
| 4 | 395 |
| 5 | 10180 |
| 6 | 322095 |
| 7 | 12194323 |
| 8 | 536197356 |
| 9 | 26904958363 |
| 10 | 1516697994964 |
[2,21,395,10180,322095,12194323,536197356, 26904958363,1516697994964] |