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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 46 |
| 3 | 626 |
| 4 | 9094 |
| 5 | 136792 |
| 6 | 2102728 |
| 7 | 32804760 |
| 8 | 517325270 |
| 9 | 8225083124 |
| 10 | 131614959262 |
| 11 | 2116988791018 |
| 12 | 34196629924584 |
| 13 | 554369366584256 |
| 14 | 9014333613083632 |
| 15 | 146961155561594176 |
| 16 | 2401364353568376054 |
| 17 | 39316907672544234028 |
| 18 | 644861670750937767370 |
[1,4,46,626,9094,136792,2102728,32804760, 517325270,8225083124,131614959262,2116988791018, 34196629924584,554369366584256,9014333613083632, 146961155561594176,2401364353568376054, 39316907672544234028,644861670750937767370] |