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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 1 |
| 2 | 6 |
| 3 | 12 |
| 4 | 420 |
| 5 | 27720 |
| 6 | 12252240 |
| 7 | 2329089562800 |
| 8 | 442720643463713815200 |
| 9 | 410555180440430163438262940577600 |
| 10 | 10514768575588513054648621420819083891762891880353600 |
| 11 | 337293588832926264639465766794841407432394382785157234228847021917234018060677390066992000 |
[2,1,6,12,420,27720,12252240,2329089562800, 442720643463713815200, 410555180440430163438262940577600, 10514768575588513054648621420819083891762891880353\ 600, 33729358883292626463946576679484140743239438278515\ 7234228847021917234018060677390066992000] |