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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 120 |
| 3 | 4416 |
| 4 | 249600 |
| 5 | 19781376 |
| 6 | 2078100480 |
| 7 | 278400270336 |
| 8 | 46222559477760 |
| 9 | 9302629468471296 |
| 10 | 2229557114964541440 |
| 11 | 627125152804037984256 |
| 12 | 204500159955172086251520 |
| 13 | 76507021194866780553609216 |
| 14 | 32543054888758773094023168000 |
| 15 | 15614979509514628186072128946176 |
[1,6,120,4416,249600,19781376,2078100480, 278400270336,46222559477760,9302629468471296, 2229557114964541440,627125152804037984256, 204500159955172086251520, 76507021194866780553609216, 32543054888758773094023168000, 15614979509514628186072128946176] |