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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 80 |
| 5 | 510 |
| 6 | 12084 |
| 7 | 164640 |
| 8 | 4272736 |
| 9 | 91935648 |
| 10 | 2769703920 |
| 11 | 80692896240 |
| 12 | 2849745645504 |
| 13 | 103479044628960 |
| 14 | 4250475820200960 |
| 15 | 183436357950387360 |
| 16 | 8649275730513361920 |
| 17 | 430735131434242736640 |
| 18 | 22999938416454315239424 |
| 19 | 1295673669960473064844800 |
[1,0,2,3,80,510,12084,164640,4272736,91935648, 2769703920,80692896240,2849745645504, 103479044628960,4250475820200960, 183436357950387360,8649275730513361920, 430735131434242736640,22999938416454315239424, 1295673669960473064844800] |