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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 60 |
| 7 | 1080 |
| 8 | 11970 |
| 9 | 105840 |
| 10 | 821592 |
| 11 | 5873760 |
| 12 | 39705630 |
| 13 | 258121080 |
| 14 | 1631169900 |
| 15 | 10096542792 |
| 16 | 61535329380 |
| 17 | 370709045280 |
| 18 | 2213740488600 |
| 19 | 13132064237040 |
| 20 | 77509384111278 |
| 21 | 455754440462040 |
| 22 | 2672268921657540 |
| 23 | 15636049474529880 |
| 24 | 91353538645037220 |
| 25 | 533180401444362672 |
[0,0,0,0,0,60,1080,11970,105840,821592,5873760, 39705630,258121080,1631169900,10096542792, 61535329380,370709045280,2213740488600, 13132064237040,77509384111278,455754440462040, 2672268921657540,15636049474529880, 91353538645037220,533180401444362672] |