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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 4 |
| 3 | -10 |
| 4 | -56 |
| 5 | 362 |
| 6 | 2764 |
| 7 | -24610 |
| 8 | -250736 |
| 9 | 2873042 |
| 10 | 36581524 |
| 11 | -512343610 |
| 12 | -7828053416 |
| 13 | 129570724922 |
| 14 | 2309644635484 |
| 15 | -44110959165010 |
| 16 | -898621108880096 |
| 17 | 19450718635716002 |
| 18 | 445777636063460644 |
| 19 | -10784052561125704810 |
| 20 | -274613643571568682776 |
| 21 | 7342627959965776406282 |
[0,2,4,-10,-56,362,2764,-24610,-250736,2873042, 36581524,-512343610,-7828053416,129570724922, 2309644635484,-44110959165010,-898621108880096, 19450718635716002,445777636063460644, -10784052561125704810,-274613643571568682776, 7342627959965776406282] |