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| n | a(n) |
|---|---|
| 2 | 2 |
| 3 | 4 |
| 4 | 26 |
| 5 | 134 |
| 6 | 958 |
| 7 | 6034 |
| 8 | 37650 |
| 9 | 242504 |
| 10 | 1590952 |
| 11 | 10574462 |
| 12 | 71449792 |
| 13 | 489478402 |
| 14 | 3388172486 |
| 15 | 23660827272 |
| 16 | 166485808342 |
[2,4,26,134,958,6034,37650,242504,1590952, 10574462,71449792,489478402,3388172486, 23660827272,166485808342] |