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| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 12 |
| 5 | 160 |
| 6 | 2450 |
| 7 | 43050 |
| 8 | 858480 |
| 9 | 19208000 |
| 10 | 477237600 |
| 11 | 13049190000 |
| 12 | 389642022000 |
| 13 | 12620614406400 |
| 14 | 440871877446000 |
| 15 | 16525943429595600 |
| 16 | 661779275661504000 |
| 17 | 28199857953915648000 |
| 18 | 1274233240573028736000 |
| 19 | 60863881753459328544000 |
[1,12,160,2450,43050,858480,19208000,477237600, 13049190000,389642022000,12620614406400, 440871877446000,16525943429595600, 661779275661504000,28199857953915648000, 1274233240573028736000,60863881753459328544000] |