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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 40 |
| 2 | 800 |
| 3 | 10680 |
| 4 | 107200 |
| 5 | 864008 |
| 6 | 5831520 |
| 7 | 33940120 |
| 8 | 174074240 |
| 9 | 800061160 |
| 10 | 3340552608 |
| 11 | 12819218040 |
| 12 | 45663942720 |
| 13 | 152270990280 |
| 14 | 478683156960 |
| 15 | 1426865410392 |
| 16 | 4052167914240 |
| 17 | 11006991835560 |
| 18 | 28691971995680 |
| 19 | 71976895917880 |
[1,40,800,10680,107200,864008,5831520,33940120, 174074240,800061160,3340552608,12819218040, 45663942720,152270990280,478683156960, 1426865410392,4052167914240,11006991835560, 28691971995680,71976895917880] |