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| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 48 |
| 3 | 132 |
| 4 | 872 |
| 5 | 3496 |
| 6 | 24888 |
| 7 | 144624 |
| 8 | 1019568 |
| 9 | 6717892 |
| 10 | 47046932 |
| 11 | 329430764 |
| 12 | 2322991876 |
| 13 | 16258944216 |
| 14 | 113059436760 |
| 15 | 777944537312 |
[6,48,132,872,3496,24888,144624,1019568,6717892, 47046932,329430764,2322991876,16258944216, 113059436760,777944537312] |