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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 23 |
| 3 | 63 |
| 4 | 432 |
| 5 | 2231 |
| 6 | 13271 |
| 7 | 81019 |
| 8 | 454822 |
| 9 | 2647771 |
| 10 | 15705120 |
| 11 | 91017707 |
| 12 | 531809890 |
| 13 | 3122451308 |
| 14 | 18251243783 |
| 15 | 106758611022 |
| 16 | 625185452829 |
| 17 | 3659138751517 |
| 18 | 21414194993312 |
| 19 | 125344300498672 |
| 20 | 733690661655699 |
| 21 | 4294342754282802 |
[3,23,63,432,2231,13271,81019,454822,2647771, 15705120,91017707,531809890,3122451308, 18251243783,106758611022,625185452829, 3659138751517,21414194993312,125344300498672, 733690661655699,4294342754282802] |