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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 24 |
| 3 | 72 |
| 4 | 3336 |
| 5 | 34800 |
| 6 | 912840 |
| 7 | 15661520 |
| 8 | 355423880 |
| 9 | 7241240160 |
| 10 | 160151370624 |
| 11 | 3461028611040 |
| 12 | 76789098028104 |
| 13 | 1700195813892576 |
| 14 | 38037857914721808 |
| 15 | 853169553940415712 |
| 16 | 19240825799184080520 |
| 17 | 435267116844063531456 |
| 18 | 9882232970998312871232 |
[1,0,24,72,3336,34800,912840,15661520,355423880, 7241240160,160151370624,3461028611040, 76789098028104,1700195813892576,38037857914721808, 853169553940415712,19240825799184080520, 435267116844063531456,9882232970998312871232] |