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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 32 |
| 5 | 150 |
| 6 | 1884 |
| 7 | 16380 |
| 8 | 249808 |
| 9 | 3255336 |
| 10 | 59596560 |
| 11 | 1037413080 |
| 12 | 22432698144 |
| 13 | 486784686960 |
| 14 | 12233449250736 |
| 15 | 316660035739320 |
| 16 | 9111729094222080 |
| 17 | 273147758526888000 |
| 18 | 8880267446524694016 |
| 19 | 301952732236006556160 |
| 20 | 10963551960785051470080 |
[0,0,2,3,32,150,1884,16380,249808,3255336, 59596560,1037413080,22432698144,486784686960, 12233449250736,316660035739320,9111729094222080, 273147758526888000,8880267446524694016, 301952732236006556160,10963551960785051470080] |