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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 2 |
| 3 | 8 |
| 4 | 20 |
| 5 | 88 |
| 6 | 264 |
| 7 | 1200 |
| 8 | 3864 |
| 9 | 17812 |
| 10 | 61044 |
| 11 | 282808 |
| 12 | 1012932 |
| 13 | 4707048 |
| 14 | 17417356 |
| 15 | 81117028 |
| 16 | 307858040 |
| 17 | 1436163312 |
[2,2,8,20,88,264,1200,3864,17812,61044,282808, 1012932,4707048,17417356,81117028,307858040, 1436163312] |