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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 15 |
| 4 | 97 |
| 5 | 745 |
| 6 | 6571 |
| 7 | 65359 |
| 8 | 723969 |
| 9 | 8842257 |
| 10 | 118091251 |
| 11 | 1712261551 |
| 12 | 26786070433 |
| 13 | 449634481465 |
| 14 | 8059974923547 |
| 15 | 153634497337455 |
| 16 | 3102367733191681 |
| 17 | 66145005096272929 |
| 18 | 1484586887025099619 |
| 19 | 34983117545622446287 |
| 20 | 863397428225495045601 |
| 21 | 22269844592814969946761 |
[1,1,3,15,97,745,6571,65359,723969,8842257, 118091251,1712261551,26786070433,449634481465, 8059974923547,153634497337455,3102367733191681, 66145005096272929,1484586887025099619, 34983117545622446287,863397428225495045601, 22269844592814969946761] |