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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | -2 |
| 4 | 6 |
| 5 | -24 |
| 6 | -820 |
| 7 | 27144 |
| 8 | -1291488 |
| 9 | 59107938 |
| 10 | -3469468244 |
| 11 | -551251146312 |
| 12 | 110380085358300 |
| 13 | -14603070221993568 |
| 14 | 1245952635117666628 |
| 15 | 29007906387788967008 |
| 16 | -20843885535528328473491 |
| 17 | -180339645015007436197752 |
| 18 | 127321605693530805940344950 |
| 19 | 281613877399819446654643101264 |
[1,1,-2,6,-24,-820,27144,-1291488,59107938, -3469468244,-551251146312,110380085358300, -14603070221993568,1245952635117666628, 29007906387788967008,-20843885535528328473491, -180339645015007436197752, 127321605693530805940344950, 281613877399819446654643101264] |