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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 12 |
| 4 | 252 |
| 5 | 9360 |
| 6 | 559800 |
| 7 | 49412160 |
| 8 | 6039794880 |
| 9 | 976299609600 |
| 10 | 201599999798400 |
| 11 | 51766949513664000 |
| 12 | 16177372653293913600 |
| 13 | 6044902527410562816000 |
| 14 | 2661334524326601925401600 |
| 15 | 1363387181797265578297344000 |
| 16 | 804077813274862776803112960000 |
| 17 | 540880443323184957954046525440000 |
[0,1,12,252,9360,559800,49412160,6039794880, 976299609600,201599999798400,51766949513664000, 16177372653293913600,6044902527410562816000, 2661334524326601925401600, 1363387181797265578297344000, 804077813274862776803112960000, 540880443323184957954046525440000] |