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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | 2 |
| 5 | 5 |
| 6 | 20 |
| 7 | 24 |
| 8 | 48 |
| 9 | 49 |
| 10 | 196 |
| 11 | 224 |
| 12 | 712 |
| 13 | 3384 |
| 14 | 3840 |
| 15 | 9828 |
| 16 | 39312 |
| 17 | 90192 |
| 18 | 218784 |
[1,1,2,2,2,5,20,24,48,49,196,224,712,3384,3840, 9828,39312,90192,218784] |