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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 4 |
| 3 | 24 |
| 4 | 24 |
| 5 | 560 |
| 6 | 2080 |
| 7 | 11088 |
| 8 | 74864 |
| 9 | 343536 |
| 10 | 2050344 |
| 11 | 11676280 |
| 12 | 61903776 |
| 13 | 363737712 |
| 14 | 2022013760 |
| 15 | 11335886864 |
| 16 | 65187410400 |
| 17 | 365627715968 |
| 18 | 2085523894756 |
| 19 | 11894205734280 |
| 20 | 67517852274384 |
| 21 | 386394626371680 |
| 22 | 2205027379874400 |
| 23 | 12602057718873040 |
| 24 | 72195482578935488 |
| 25 | 413235574714857360 |
[1,0,4,24,24,560,2080,11088,74864,343536,2050344, 11676280,61903776,363737712,2022013760, 11335886864,65187410400,365627715968, 2085523894756,11894205734280,67517852274384, 386394626371680,2205027379874400, 12602057718873040,72195482578935488, 413235574714857360] |