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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 74 |
| 4 | 636 |
| 5 | 5996 |
| 6 | 60500 |
| 7 | 640536 |
| 8 | 7032004 |
| 9 | 79442404 |
| 10 | 918460996 |
| 11 | 10822792116 |
| 12 | 129586488144 |
| 13 | 1572865007248 |
| 14 | 19316089471728 |
| 15 | 239655258634016 |
| 16 | 3000258698957516 |
| 17 | 37860881282339972 |
| 18 | 481184329951150276 |
| 19 | 6154697345463251892 |
| 20 | 79178658464829291656 |
| 21 | 1023964603651763072264 |
[1,2,10,74,636,5996,60500,640536,7032004,79442404, 918460996,10822792116,129586488144,1572865007248, 19316089471728,239655258634016,3000258698957516, 37860881282339972,481184329951150276, 6154697345463251892,79178658464829291656, 1023964603651763072264] |