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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 21 |
| 3 | 160 |
| 4 | 1320 |
| 5 | 11511 |
| 6 | 104451 |
| 7 | 976317 |
| 8 | 9337182 |
| 9 | 90937403 |
| 10 | 898861308 |
| 11 | 8994246132 |
| 12 | 90932043400 |
| 13 | 927452701605 |
| 14 | 9531607969788 |
| 15 | 98609173435172 |
| 16 | 1026121044859890 |
| 17 | 10733030463200814 |
| 18 | 112783955395845926 |
| 19 | 1190060614961391945 |
| 20 | 12604133970419399208 |
| 21 | 133945684546835994915 |
[1,3,21,160,1320,11511,104451,976317,9337182, 90937403,898861308,8994246132,90932043400, 927452701605,9531607969788,98609173435172, 1026121044859890,10733030463200814, 112783955395845926,1190060614961391945, 12604133970419399208,133945684546835994915] |