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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 5 |
| 5 | 22 |
| 6 | 122 |
| 7 | 787 |
| 8 | 5852 |
| 9 | 49330 |
| 10 | 465112 |
| 11 | 4850460 |
| 12 | 55433829 |
| 13 | 688963306 |
| 14 | 9251792972 |
| 15 | 133490155743 |
| 16 | 2059562402902 |
| 17 | 33835668047686 |
| 18 | 589707357402530 |
| 19 | 10867464157846629 |
| 20 | 211139303638163096 |
| 21 | 4313274345751046120 |
[1,0,0,1,5,22,122,787,5852,49330,465112,4850460, 55433829,688963306,9251792972,133490155743, 2059562402902,33835668047686,589707357402530, 10867464157846629,211139303638163096, 4313274345751046120] |