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| n | a(n) |
|---|---|
| 1 | 81 |
| 2 | 312 |
| 3 | 1240 |
| 4 | 4752 |
| 5 | 19128 |
| 6 | 72736 |
| 7 | 290112 |
| 8 | 1110080 |
| 9 | 4459296 |
| 10 | 16979328 |
| 11 | 67827328 |
| 12 | 259259648 |
| 13 | 1040224128 |
| 14 | 3964054016 |
| 15 | 15850143744 |
| 16 | 60545315840 |
| 17 | 242745766400 |
| 18 | 925519968256 |
| 19 | 3702814799872 |
| 20 | 14138549342208 |
| 21 | 56660164196352 |
[81,312,1240,4752,19128,72736,290112,1110080, 4459296,16979328,67827328,259259648,1040224128, 3964054016,15850143744,60545315840,242745766400, 925519968256,3702814799872,14138549342208, 56660164196352] |