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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 19 |
| 5 | 208 |
| 6 | 480 |
| 7 | 3011 |
| 8 | 7185 |
| 9 | 20169 |
| 10 | 35438 |
| 11 | 111232 |
| 12 | 162062 |
| 13 | 422841 |
| 14 | 633226 |
| 15 | 1024370 |
| 16 | 1576122 |
| 17 | 3315790 |
| 18 | 4240974 |
| 19 | 8204951 |
| 20 | 10654475 |
| 21 | 15310713 |
[1,2,5,19,208,480,3011,7185,20169,35438,111232, 162062,422841,633226,1024370,1576122,3315790, 4240974,8204951,10654475,15310713] |