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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 20 |
| 3 | 630 |
| 4 | 4480 |
| 5 | 36288 |
| 6 | 3326400 |
| 7 | 444787200 |
| 8 | 5811886080 |
| 9 | 81729648000 |
| 10 | 19760412672000 |
| 11 | 6082255020441600 |
| 12 | 115852476579840000 |
| 13 | 2322315553259520000 |
| 14 | 1077167364120207360000 |
| 15 | 24817936069329577574400 |
| 16 | 596585001666576384000000 |
| 17 | 14936720782466875392000000 |
[1,20,630,4480,36288,3326400,444787200,5811886080, 81729648000,19760412672000,6082255020441600, 115852476579840000,2322315553259520000, 1077167364120207360000,24817936069329577574400, 596585001666576384000000, 14936720782466875392000000] |