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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 240 |
| 2 | 190800 |
| 3 | 16833600 |
| 4 | 397680720 |
| 5 | 4630540320 |
| 6 | 34416204480 |
| 7 | 187485916800 |
| 8 | 814900050000 |
| 9 | 2975524213680 |
| 10 | 9486523478880 |
| 11 | 27053074226880 |
| 12 | 70486147972800 |
| 13 | 169930956669600 |
| 14 | 384163682797440 |
| 15 | 820166912933760 |
[1,240,190800,16833600,397680720,4630540320, 34416204480,187485916800,814900050000, 2975524213680,9486523478880,27053074226880, 70486147972800,169930956669600,384163682797440, 820166912933760] |