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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 8 |
| 5 | 80 |
| 6 | 528 |
| 7 | 2912 |
| 8 | 14592 |
| 9 | 69120 |
| 10 | 316160 |
| 11 | 1413632 |
| 12 | 6223872 |
| 13 | 27103232 |
| 14 | 117067776 |
| 15 | 502456320 |
| 16 | 2145517568 |
| 17 | 9122349056 |
| 18 | 38644678656 |
| 19 | 163186343936 |
| 20 | 687144960000 |
| 21 | 2886107922432 |
| 22 | 12094385684480 |
| 23 | 50577004298240 |
| 24 | 211105074905088 |
| 25 | 879606785638400 |
[0,0,0,0,8,80,528,2912,14592,69120,316160,1413632, 6223872,27103232,117067776,502456320,2145517568, 9122349056,38644678656,163186343936,687144960000, 2886107922432,12094385684480,50577004298240, 211105074905088,879606785638400] |