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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 18 |
| 2 | 216 |
| 3 | 3240 |
| 4 | 58320 |
| 5 | 1224720 |
| 6 | 29393280 |
| 7 | 793618560 |
| 8 | 23808556800 |
| 9 | 785682374400 |
| 10 | 28284565478400 |
| 11 | 1103098053657600 |
| 12 | 46330118253619200 |
| 13 | 2084855321412864000 |
| 14 | 100073055427817472000 |
| 15 | 5103725826818691072000 |
| 16 | 275601194648209317888000 |
[2,18,216,3240,58320,1224720,29393280,793618560, 23808556800,785682374400,28284565478400, 1103098053657600,46330118253619200, 2084855321412864000,100073055427817472000, 5103725826818691072000,275601194648209317888000] |