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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 2 |
| 3 | 3 |
| 4 | 7 |
| 5 | 31 |
| 6 | 241 |
| 7 | 3121 |
| 8 | 65521 |
| 9 | 2227681 |
| 10 | 122522401 |
| 11 | 10904493601 |
| 12 | 1570247078401 |
| 13 | 365867569267201 |
| 14 | 137932073613734401 |
| 15 | 84138564904377984001 |
| 16 | 83044763560621070208001 |
| 17 | 132622487406311849122176001 |
| 18 | 342696507457909818131702784001 |
[2,2,3,7,31,241,3121,65521,2227681,122522401, 10904493601,1570247078401,365867569267201, 137932073613734401,84138564904377984001, 83044763560621070208001, 132622487406311849122176001, 342696507457909818131702784001] |