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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 20 |
| 7 | 0 |
| 8 | 630 |
| 9 | 4480 |
| 10 | 36288 |
| 11 | 0 |
| 12 | 3326400 |
| 13 | 0 |
| 14 | 444787200 |
| 15 | 5811886080 |
| 16 | 81729648000 |
| 17 | 0 |
| 18 | 19760412672000 |
| 19 | 0 |
| 20 | 6082255020441600 |
| 21 | 115852476579840000 |
| 22 | 2322315553259520000 |
| 23 | 0 |
| 24 | 1077167364120207360000 |
| 25 | 24817936069329577574400 |
[1,0,0,0,0,20,0,630,4480,36288,0,3326400,0, 444787200,5811886080,81729648000,0,19760412672000, 0,6082255020441600,115852476579840000, 2322315553259520000,0,1077167364120207360000, 24817936069329577574400] |