| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 3 |
| 4 | -12 |
| 5 | 55 |
| 6 | -273 |
| 7 | 1431 |
| 8 | -7837 |
| 9 | 44726 |
| 10 | -266381 |
| 11 | 1658300 |
| 12 | -10768609 |
| 13 | 72407500 |
| 14 | -498510748 |
| 15 | 3477131466 |
| 16 | -24461950817 |
| 17 | 174793982029 |
| 18 | -1294469021982 |
| 19 | 10177610535232 |
| 20 | -85391010070808 |
| 21 | 741460526149745 |
| 22 | -6291905077685633 |
[1,-1,3,-12,55,-273,1431,-7837,44726,-266381, 1658300,-10768609,72407500,-498510748,3477131466, -24461950817,174793982029,-1294469021982, 10177610535232,-85391010070808,741460526149745, -6291905077685633] |