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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 4 |
| 4 | 344 |
| 5 | 8760 |
| 6 | 157504 |
| 7 | 2388204 |
| 8 | 32737984 |
| 9 | 419969088 |
| 10 | 5141235840 |
| 11 | 60795581132 |
| 12 | 700024311536 |
| 13 | 7892352548080 |
[0,0,4,344,8760,157504,2388204,32737984,419969088, 5141235840,60795581132,700024311536,7892352548080] |