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| n | a(n) |
|---|---|
| 1 | 1248 |
| 2 | 4312 |
| 3 | 14800 |
| 4 | 51220 |
| 5 | 177520 |
| 6 | 617600 |
| 7 | 2152744 |
| 8 | 7527124 |
| 9 | 26367488 |
| 10 | 92632604 |
| 11 | 326009192 |
| 12 | 1150507192 |
| 13 | 4067126368 |
| 14 | 14415310196 |
| 15 | 51176035576 |
| 16 | 182134771204 |
| 17 | 649220616600 |
| 18 | 2319643303000 |
| 19 | 8300224862256 |
| 20 | 29766948184132 |
| 21 | 106901780220416 |
[1248,4312,14800,51220,177520,617600,2152744, 7527124,26367488,92632604,326009192,1150507192, 4067126368,14415310196,51176035576,182134771204, 649220616600,2319643303000,8300224862256, 29766948184132,106901780220416] |