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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 51 |
| 3 | 346 |
| 4 | 2405 |
| 5 | 16812 |
| 6 | 117655 |
| 7 | 823550 |
| 8 | 5764809 |
| 9 | 40353616 |
| 10 | 282475259 |
| 11 | 1977326754 |
| 12 | 13841287213 |
| 13 | 96889010420 |
| 14 | 678223072863 |
| 15 | 4747561509958 |
| 16 | 33232930569617 |
| 17 | 232630513987224 |
| 18 | 1628413597910467 |
| 19 | 11398895185373162 |
| 20 | 79792266297612021 |
[1,8,51,346,2405,16812,117655,823550,5764809, 40353616,282475259,1977326754,13841287213, 96889010420,678223072863,4747561509958, 33232930569617,232630513987224,1628413597910467, 11398895185373162,79792266297612021] |