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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 3 |
| 5 | 0 |
| 6 | 1 |
| 7 | 68 |
| 8 | 1200 |
| 9 | 7268 |
| 10 | 20025 |
| 11 | 27750 |
| 12 | 18900 |
| 13 | 5040 |
| 14 | 0 |
| 15 | 0 |
| 16 | 0 |
| 17 | 0 |
| 18 | 1 |
| 19 | 93022 |
| 20 | 293878020 |
| 21 | 90807857080 |
| 22 | 7503022894800 |
| 23 | 258528829444320 |
| 24 | 4681671089961600 |
| 25 | 50981530073846400 |
| 26 | 363246007692204000 |
[1,1,4,3,0,1,68,1200,7268,20025,27750,18900,5040, 0,0,0,0,1,93022,293878020,90807857080, 7503022894800,258528829444320,4681671089961600, 50981530073846400,363246007692204000] |