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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 4 |
| 2 | 31 |
| 3 | 1674 |
| 4 | 4989191 |
| 5 | 44334502845080 |
| 6 | 3500783582875029181027036603 |
| 7 | 21827907538883637012326748457700300661358717434156476363 |
[2,4,31,1674,4989191,44334502845080, 3500783582875029181027036603, 21827907538883637012326748457700300661358717434156\ 476363] |