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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 4 |
| 6 | 46 |
| 7 | 394 |
| 8 | 3025 |
| 9 | 22707 |
| 10 | 167732 |
| 11 | 1241417 |
| 12 | 9221624 |
| 13 | 68936674 |
| 14 | 518574100 |
| 15 | 3925132946 |
| 16 | 29878869619 |
| 17 | 228629549175 |
| 18 | 1757697391087 |
| 19 | 13570818452472 |
| 20 | 105182527335313 |
| 21 | 818093680980786 |
| 22 | 6383353461322488 |
[0,0,0,0,4,46,394,3025,22707,167732,1241417, 9221624,68936674,518574100,3925132946,29878869619, 228629549175,1757697391087,13570818452472, 105182527335313,818093680980786,6383353461322488] |