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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 0 |
| 4 | 450 |
| 5 | 4480 |
| 6 | 1786050 |
| 7 | 61776000 |
| 8 | 37240453250 |
| 9 | 2713505184000 |
| 10 | 2464296285701250 |
| 11 | 308006231110240000 |
| 12 | 397784819452992221250 |
| 13 | 76036685958833418000000 |
| 14 | 132964856302641623934781250 |
[0,2,0,450,4480,1786050,61776000,37240453250, 2713505184000,2464296285701250,308006231110240000, 397784819452992221250,76036685958833418000000, 132964856302641623934781250] |