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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 12 |
| 4 | 62 |
| 5 | 344 |
| 6 | 1864 |
| 7 | 10162 |
| 8 | 55324 |
| 9 | 301278 |
| 10 | 1640592 |
| 11 | 8933808 |
| 12 | 48648834 |
| 13 | 264916012 |
| 14 | 1442593630 |
| 15 | 7855607976 |
| 16 | 42777519416 |
| 17 | 232943926258 |
| 18 | 1268490401852 |
| 19 | 6907533179198 |
| 20 | 37614801461920 |
| 21 | 204830473095648 |
| 22 | 1115399286396802 |
[0,2,12,62,344,1864,10162,55324,301278,1640592, 8933808,48648834,264916012,1442593630,7855607976, 42777519416,232943926258,1268490401852, 6907533179198,37614801461920,204830473095648, 1115399286396802] |