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| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 36 |
| 5 | 990 |
| 6 | 25740 |
| 7 | 675675 |
| 8 | 18378360 |
| 9 | 523783260 |
| 10 | 15713497800 |
| 11 | 496939367925 |
| 12 | 16564645597500 |
| 13 | 581419060472250 |
| 14 | 21459648959248500 |
| 15 | 831561397170879375 |
| 16 | 33774185977401870000 |
| 17 | 1435402904039579475000 |
| 18 | 63731888939357328690000 |
[1,36,990,25740,675675,18378360,523783260, 15713497800,496939367925,16564645597500, 581419060472250,21459648959248500, 831561397170879375,33774185977401870000, 1435402904039579475000,63731888939357328690000] |