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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 48 |
| 3 | 12 |
| 4 | 229 |
| 5 | 2170 |
| 6 | 6418 |
| 7 | 58139 |
| 8 | 462269 |
| 9 | 2322276 |
| 10 | 16986669 |
| 11 | 128454665 |
| 12 | 778933970 |
| 13 | 5406879133 |
| 14 | 38760904917 |
| 15 | 253109636772 |
| 16 | 1732629194130 |
| 17 | 12086047164497 |
| 18 | 81183351061250 |
| 19 | 553954840007329 |
| 20 | 3816972699796285 |
| 21 | 25909423046395072 |
[0,48,12,229,2170,6418,58139,462269,2322276, 16986669,128454665,778933970,5406879133, 38760904917,253109636772,1732629194130, 12086047164497,81183351061250,553954840007329, 3816972699796285,25909423046395072] |