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| n | a(n) |
|---|---|
| 3 | 0 |
| 4 | 0 |
| 5 | 128 |
| 6 | 6912 |
| 7 | 301056 |
| 8 | 13107200 |
| 9 | 604661760 |
| 10 | 30105600000 |
| 11 | 1625414303744 |
| 12 | 95105071448064 |
| 13 | 6014219459788800 |
| 14 | 409597814515957760 |
| 15 | 29930757120000000000 |
| 16 | 2338124811342685667328 |
| 17 | 194579196865600687702016 |
| 18 | 17194638200501483392204800 |
| 19 | 1608612930338829120118456320 |
| 20 | 158879430213632000000000000000 |
[0,0,128,6912,301056,13107200,604661760, 30105600000,1625414303744,95105071448064, 6014219459788800,409597814515957760, 29930757120000000000,2338124811342685667328, 194579196865600687702016, 17194638200501483392204800, 1608612930338829120118456320, 158879430213632000000000000000] |