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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 0 |
| 3 | 4 |
| 4 | 5 |
| 5 | 96 |
| 6 | 548 |
| 7 | 7908 |
| 8 | 84696 |
| 9 | 1331840 |
| 10 | 20255774 |
| 11 | 372819387 |
| 12 | 7170089146 |
| 13 | 154824436840 |
| 14 | 3558826861734 |
| 15 | 88938133663711 |
| 16 | 2367074592366594 |
| 17 | 67402755251544804 |
| 18 | 2034875403034891874 |
| 19 | 65102692993820702700 |
| 20 | 2196725886835707259041 |
| 21 | 78036983096041464230268 |
[1,1,0,4,5,96,548,7908,84696,1331840,20255774, 372819387,7170089146,154824436840,3558826861734, 88938133663711,2367074592366594,67402755251544804, 2034875403034891874,65102692993820702700, 2196725886835707259041,78036983096041464230268] |