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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 18 |
| 4 | 180 |
| 5 | 3060 |
| 6 | 101160 |
| 7 | 3807720 |
| 8 | 174986280 |
| 9 | 10699554600 |
| 10 | 927701102160 |
| 11 | 95030461809360 |
| 12 | 10905467528783520 |
| 13 | 1431935974242053280 |
| 14 | 222906109589537774400 |
| 15 | 42471495822490670295360 |
| 16 | 9447237366839585591438160 |
| 17 | 2329156499421828313498781520 |
[1,2,18,180,3060,101160,3807720,174986280, 10699554600,927701102160,95030461809360, 10905467528783520,1431935974242053280, 222906109589537774400,42471495822490670295360, 9447237366839585591438160, 2329156499421828313498781520] |