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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 22 |
| 3 | 108 |
| 4 | 460 |
| 5 | 2088 |
| 6 | 9208 |
| 7 | 41136 |
| 8 | 182704 |
| 9 | 813600 |
| 10 | 3618784 |
| 11 | 16104384 |
| 12 | 71651008 |
| 13 | 318820992 |
| 14 | 1418569600 |
| 15 | 6311953152 |
| 16 | 28084886272 |
| 17 | 124963582464 |
| 18 | 556023840256 |
| 19 | 2474023050240 |
| 20 | 11008138832896 |
| 21 | 48980603529216 |
| 22 | 217938687588352 |
[1,6,22,108,460,2088,9208,41136,182704,813600, 3618784,16104384,71651008,318820992,1418569600, 6311953152,28084886272,124963582464,556023840256, 2474023050240,11008138832896,48980603529216, 217938687588352] |