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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 16 |
| 5 | 74 |
| 6 | 368 |
| 7 | 1924 |
| 8 | 10496 |
| 9 | 65446 |
| 10 | 426596 |
| 11 | 3048508 |
| 12 | 22901328 |
| 13 | 189677816 |
| 14 | 1628971852 |
| 15 | 15211951462 |
| 16 | 146663420606 |
[1,2,6,16,74,368,1924,10496,65446,426596,3048508, 22901328,189677816,1628971852,15211951462, 146663420606] |