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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | 362880 |
| 10 | 3265920 |
| 11 | 33022080 |
| 12 | 369774720 |
| 13 | 4536362880 |
| 14 | 60451816320 |
| 15 | 869007242880 |
| 16 | 13397819541120 |
| 17 | 220448163358080 |
| 18 | 3854801333416320 |
| 19 | 71370457471716480 |
| 20 | 1394586705296776320 |
| 21 | 28676809138124407680 |
| 22 | 618948032364173877120 |
[0,0,0,0,0,0,0,0,362880,3265920,33022080, 369774720,4536362880,60451816320,869007242880, 13397819541120,220448163358080,3854801333416320, 71370457471716480,1394586705296776320, 28676809138124407680,618948032364173877120] |