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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 12 |
| 3 | 28 |
| 4 | 48 |
| 5 | 240 |
| 6 | 944 |
| 7 | 5344 |
| 8 | 23408 |
| 9 | 133808 |
| 10 | 751008 |
| 11 | 5222768 |
| 12 | 37898776 |
| 13 | 292271304 |
| 14 | 2346665448 |
| 15 | 20499852656 |
[1,3,12,28,48,240,944,5344,23408,133808,751008, 5222768,37898776,292271304,2346665448,20499852656] |