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| n | a(n) |
|---|---|
| 1 | 81 |
| 2 | 344 |
| 3 | 1472 |
| 4 | 6368 |
| 5 | 27280 |
| 6 | 115584 |
| 7 | 494592 |
| 8 | 2139648 |
| 9 | 9166080 |
| 10 | 38836224 |
| 11 | 166182912 |
| 12 | 718921728 |
| 13 | 3079802880 |
| 14 | 13048971264 |
| 15 | 55837458432 |
| 16 | 241557700608 |
| 17 | 1034813767680 |
| 18 | 4384454344704 |
| 19 | 18761386033152 |
| 20 | 81163387404288 |
| 21 | 347697425940480 |
[81,344,1472,6368,27280,115584,494592,2139648, 9166080,38836224,166182912,718921728,3079802880, 13048971264,55837458432,241557700608, 1034813767680,4384454344704,18761386033152, 81163387404288,347697425940480] |