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| n | a(n) |
|---|---|
| 0 | -2 |
| 1 | -4 |
| 2 | -4 |
| 3 | 26 |
| 4 | 272 |
| 5 | 1826 |
| 6 | 10736 |
| 7 | 59426 |
| 8 | 318272 |
| 9 | 1670786 |
| 10 | 8656976 |
| 11 | 44454626 |
| 12 | 226827872 |
| 13 | 1151991746 |
| 14 | 5830280816 |
| 15 | 29429454626 |
| 16 | 148249811072 |
| 17 | 745630312706 |
| 18 | 3745590106256 |
| 19 | 18797445635426 |
| 20 | 94264432179872 |
| 21 | 472428649241666 |
| 22 | 2366562219717296 |
| 23 | 11850466059333026 |
| 24 | 59322887352366272 |
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