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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 20 |
| 6 | 840 |
| 7 | 26250 |
| 8 | 773920 |
| 9 | 23166360 |
| 10 | 724253040 |
| 11 | 23921630810 |
| 12 | 838352908800 |
| 13 | 31203417745500 |
| 14 | 1232550480801640 |
| 15 | 51590674307982810 |
| 16 | 2283883442833836480 |
| 17 | 106713738151299297200 |
| 18 | 5251783507905871571040 |
| 19 | 271673904611812139017650 |
| 20 | 14743195769771119241426080 |
[0,0,0,0,0,20,840,26250,773920,23166360,724253040, 23921630810,838352908800,31203417745500, 1232550480801640,51590674307982810, 2283883442833836480,106713738151299297200, 5251783507905871571040,271673904611812139017650, 14743195769771119241426080] |