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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 500 |
| 6 | 16980 |
| 7 | 342160 |
| 8 | 5486040 |
| 9 | 77926380 |
| 10 | 1031160060 |
| 11 | 13047426920 |
| 12 | 160124426880 |
| 13 | 1921105846660 |
| 14 | 22632779709540 |
| 15 | 262513678889280 |
| 16 | 3002768326532520 |
| 17 | 33914184260797340 |
| 18 | 378596540805849420 |
| 19 | 4181330954328313240 |
| 20 | 45727913513193402960 |
| 21 | 495618273676457274420 |
[0,0,0,0,0,500,16980,342160,5486040,77926380, 1031160060,13047426920,160124426880,1921105846660, 22632779709540,262513678889280,3002768326532520, 33914184260797340,378596540805849420, 4181330954328313240,45727913513193402960, 495618273676457274420] |