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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 24 |
| 5 | -120 |
| 6 | 360 |
| 7 | -840 |
| 8 | 21840 |
| 9 | -365904 |
| 10 | 3633840 |
| 11 | -26619120 |
| 12 | 239512680 |
| 13 | -3943797000 |
| 14 | 69258333144 |
| 15 | -997361197560 |
| 16 | 12707273822880 |
| 17 | -179576670930720 |
| 18 | 3215428464641760 |
| 19 | -62865157116396384 |
| 20 | 1167555972633639480 |
| 21 | -20756362432008412440 |
[1,0,0,0,24,-120,360,-840,21840,-365904,3633840, -26619120,239512680,-3943797000,69258333144, -997361197560,12707273822880,-179576670930720, 3215428464641760,-62865157116396384, 1167555972633639480,-20756362432008412440] |