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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 12 |
| 3 | 64 |
| 4 | 404 |
| 5 | 2352 |
| 6 | 14396 |
| 7 | 85608 |
| 8 | 517796 |
| 9 | 3100928 |
| 10 | 18678652 |
| 11 | 112130536 |
| 12 | 674473028 |
| 13 | 4052292096 |
| 14 | 24363059260 |
| 15 | 146416625608 |
| 16 | 880136072420 |
| 17 | 5289934135040 |
| 18 | 31796930379452 |
| 19 | 191117281480168 |
| 20 | 1148752620931652 |
| 21 | 6904721644495296 |
| 22 | 41502080416224764 |
[1,2,12,64,404,2352,14396,85608,517796,3100928, 18678652,112130536,674473028,4052292096, 24363059260,146416625608,880136072420, 5289934135040,31796930379452,191117281480168, 1148752620931652,6904721644495296, 41502080416224764] |