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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 3 |
| 6 | 17 |
| 7 | 104 |
| 8 | 740 |
| 9 | 6005 |
| 10 | 54717 |
| 11 | 553253 |
| 12 | 6147263 |
| 13 | 74450193 |
| 14 | 976124760 |
| 15 | 13774204958 |
| 16 | 208143541601 |
| 17 | 3353423725801 |
| 18 | 57380805974819 |
| 19 | 1039230152655057 |
| 20 | 19860842917407765 |
| 21 | 399423618672311729 |
[1,0,0,0,0,3,17,104,740,6005,54717,553253,6147263, 74450193,976124760,13774204958,208143541601, 3353423725801,57380805974819,1039230152655057, 19860842917407765,399423618672311729] |