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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 66 |
| 3 | 560 |
| 4 | 4876 |
| 5 | 43488 |
| 6 | 396664 |
| 7 | 3695168 |
| 8 | 35114640 |
| 9 | 340039808 |
| 10 | 3352381984 |
| 11 | 33619852032 |
| 12 | 342711219904 |
| 13 | 3548566208000 |
| 14 | 37299021381504 |
| 15 | 397752024876032 |
| 16 | 4300986840453376 |
| 17 | 47135959519660032 |
| 18 | 523321228732695040 |
| 19 | 5883464372569321472 |
| 20 | 66953921672396983296 |
[1,8,66,560,4876,43488,396664,3695168,35114640, 340039808,3352381984,33619852032,342711219904, 3548566208000,37299021381504,397752024876032, 4300986840453376,47135959519660032, 523321228732695040,5883464372569321472, 66953921672396983296] |