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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 6 |
| 4 | 50 |
| 5 | 1220 |
| 6 | 42122 |
| 7 | 2278248 |
| 8 | 182111666 |
| 9 | 21094774212 |
| 10 | 3479970392642 |
| 11 | 807001730170592 |
| 12 | 260359119927269882 |
| 13 | 115887302333840512956 |
| 14 | 70677462143507496419690 |
| 15 | 58725460618979611312258632 |
[1,0,6,50,1220,42122,2278248,182111666, 21094774212,3479970392642,807001730170592, 260359119927269882,115887302333840512956, 70677462143507496419690, 58725460618979611312258632] |