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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 45 |
| 4 | 436 |
| 5 | 5345 |
| 6 | 79716 |
| 7 | 1403689 |
| 8 | 28518736 |
| 9 | 656835633 |
| 10 | 16913175310 |
| 11 | 481496895121 |
| 12 | 15017297246832 |
| 13 | 509223994442449 |
| 14 | 18652724643726460 |
| 15 | 733989868341011325 |
| 16 | 30879549535458286096 |
| 17 | 1383134389475750109089 |
| 18 | 65714992805644764521724 |
| 19 | 3300990246208225995520681 |
[0,1,6,45,436,5345,79716,1403689,28518736, 656835633,16913175310,481496895121,15017297246832, 509223994442449,18652724643726460, 733989868341011325,30879549535458286096, 1383134389475750109089,65714992805644764521724, 3300990246208225995520681] |