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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 5 |
| 6 | 28 |
| 7 | 177 |
| 8 | 1269 |
| 9 | 10365 |
| 10 | 95019 |
| 11 | 966032 |
| 12 | 10787362 |
| 13 | 131246245 |
| 14 | 1728075562 |
| 15 | 24481070469 |
| 16 | 371296235455 |
| 17 | 6002622473192 |
| 18 | 103045019123132 |
| 19 | 1871984514070244 |
| 20 | 35879703186346359 |
| 21 | 723574014257984910 |
[1,0,0,0,1,5,28,177,1269,10365,95019,966032, 10787362,131246245,1728075562,24481070469, 371296235455,6002622473192,103045019123132, 1871984514070244,35879703186346359, 723574014257984910] |