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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 16 |
| 3 | 90 |
| 4 | 784 |
| 5 | 5856 |
| 6 | 42849 |
| 7 | 353808 |
| 8 | 2792241 |
| 9 | 21195317 |
| 10 | 182223001 |
| 11 | 1372615690 |
| 12 | 11550015841 |
| 13 | 91115397450 |
| 14 | 745461286801 |
| 15 | 5965914998428 |
| 16 | 49005684164836 |
| 17 | 389634565985060 |
| 18 | 3219980044337424 |
[2,16,90,784,5856,42849,353808,2792241,21195317, 182223001,1372615690,11550015841,91115397450, 745461286801,5965914998428,49005684164836, 389634565985060,3219980044337424] |