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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 28 |
| 5 | 180 |
| 6 | 1446 |
| 7 | 13888 |
| 8 | 156472 |
| 9 | 2034000 |
| 10 | 29724490 |
| 11 | 476806176 |
| 12 | 8502508884 |
| 13 | 174802753216 |
| 14 | 3768345692398 |
| 15 | 63300353418240 |
| 16 | 1386349221087856 |
| 17 | 149879079531401472 |
| 18 | 5097575010920072850 |
| 19 | -780487993325688128000 |
| 20 | -32524149870689487270260 |
| 21 | 10927977097616993825596416 |
| 22 | 490896441869732669067535414 |
| 23 | -213936255246865273137807851520 |
| 24 | -10450262329586550037066790750808 |
| 25 | 6047981224337998054714885264691200 |
[1,2,6,28,180,1446,13888,156472,2034000,29724490, 476806176,8502508884,174802753216,3768345692398, 63300353418240,1386349221087856, 149879079531401472,5097575010920072850, -780487993325688128000,-32524149870689487270260, 10927977097616993825596416, 490896441869732669067535414, -213936255246865273137807851520, -10450262329586550037066790750808, 6047981224337998054714885264691200] |