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| n | a(n) |
|---|---|
| 1 | 20 |
| 2 | 400 |
| 3 | 5304 |
| 4 | 68064 |
| 5 | 852448 |
| 6 | 10682432 |
| 7 | 133744640 |
| 8 | 1674569728 |
| 9 | 20965958400 |
| 10 | 262498839552 |
| 11 | 3286544012800 |
| 12 | 41148269700608 |
| 13 | 515185556441600 |
| 14 | 6450238643180032 |
| 15 | 80758433426035200 |
| 16 | 1011113686205526528 |
[20,400,5304,68064,852448,10682432,133744640, 1674569728,20965958400,262498839552,3286544012800, 41148269700608,515185556441600,6450238643180032, 80758433426035200,1011113686205526528] |