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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 48 |
| 4 | 2064 |
| 5 | 167280 |
| 6 | 23136480 |
| 7 | 4824953280 |
| 8 | 1417422988800 |
| 9 | 557894688341760 |
| 10 | 283527366696806400 |
| 11 | 180770613278509900800 |
| 12 | 141310830114906688051200 |
| 13 | 132919668653581764822067200 |
| 14 | 148111929489204170921816985600 |
| 15 | 192952383265326280925512415232000 |
[1,1,4,48,2064,167280,23136480,4824953280, 1417422988800,557894688341760,283527366696806400, 180770613278509900800,141310830114906688051200, 132919668653581764822067200, 148111929489204170921816985600, 192952383265326280925512415232000] |