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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | -4 |
| 3 | 6 |
| 4 | 16 |
| 5 | -119 |
| 6 | 240 |
| 7 | 630 |
| 8 | -5656 |
| 9 | 13044 |
| 10 | 31568 |
| 11 | -323102 |
| 12 | 816172 |
| 13 | 1772553 |
| 14 | -20373748 |
| 15 | 55339784 |
| 16 | 105991968 |
| 17 | -1366239119 |
| 18 | 3950894080 |
| 19 | 6570520544 |
| 20 | -95534073488 |
| 21 | 292319792622 |
| 22 | 414994066768 |
| 23 | -6884779019086 |
| 24 | 22198354364212 |
| 25 | 26341578132594 |
| 26 | -507524582140912 |
[1,1,-4,6,16,-119,240,630,-5656,13044,31568, -323102,816172,1772553,-20373748,55339784, 105991968,-1366239119,3950894080,6570520544, -95534073488,292319792622,414994066768, -6884779019086,22198354364212,26341578132594, -507524582140912] |