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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 64 |
| 3 | 576 |
| 4 | 4672 |
| 5 | 37440 |
| 6 | 299584 |
| 7 | 2396736 |
| 8 | 19173952 |
| 9 | 153391680 |
| 10 | 1227133504 |
| 11 | 9817068096 |
| 12 | 78536544832 |
| 13 | 628292358720 |
| 14 | 5026338869824 |
| 15 | 40210710958656 |
| 16 | 321685687669312 |
| 17 | 2573485501354560 |
| 18 | 20587884010836544 |
| 19 | 164703072086692416 |
| 20 | 1317624576693539392 |
| 21 | 10540996613548315200 |
[0,64,576,4672,37440,299584,2396736,19173952, 153391680,1227133504,9817068096,78536544832, 628292358720,5026338869824,40210710958656, 321685687669312,2573485501354560, 20587884010836544,164703072086692416, 1317624576693539392,10540996613548315200] |