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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 12 |
| 4 | 32 |
| 5 | 270 |
| 6 | 840 |
| 7 | 7812 |
| 8 | 23808 |
| 9 | 178452 |
| 10 | 583880 |
| 11 | 4882812 |
| 12 | 12434160 |
| 13 | 122070312 |
| 14 | 391954136 |
| 15 | 2630952180 |
[0,0,12,32,270,840,7812,23808,178452,583880, 4882812,12434160,122070312,391954136,2630952180] |