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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 8 |
| 5 | 84 |
| 6 | 180 |
| 7 | 3044 |
| 8 | 8064 |
| 9 | 193248 |
| 10 | 604800 |
| 11 | 19056960 |
| 12 | 68428800 |
| 13 | 2699672832 |
| 14 | 10897286400 |
| 15 | 520105017600 |
| 16 | 2324754432000 |
| 17 | 130859579289600 |
| 18 | 640237370572800 |
| 19 | 41680704936960000 |
| 20 | 221172909834240000 |
| 21 | 16397141420298240000 |
| 22 | 93666727314800640000 |
| 23 | 7809290721329061888000 |
| 24 | 47726800133326110720000 |
[1,1,1,5,8,84,180,3044,8064,193248,604800, 19056960,68428800,2699672832,10897286400, 520105017600,2324754432000,130859579289600, 640237370572800,41680704936960000, 221172909834240000,16397141420298240000, 93666727314800640000,7809290721329061888000, 47726800133326110720000] |