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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 34 |
| 5 | 284 |
| 6 | 2698 |
| 7 | 28116 |
| 8 | 314558 |
| 9 | 3726504 |
| 10 | 46310523 |
| 11 | 599691087 |
| 12 | 8051875596 |
| 13 | 111674902936 |
| 14 | 1595269110991 |
| 15 | 23416737953975 |
| 16 | 352551682694096 |
| 17 | 5435771974479840 |
| 18 | 85722307390977058 |
| 19 | 1381216396128765272 |
| 20 | 22718307467700650259 |
| 21 | 381156536404199989205 |
[1,1,5,34,284,2698,28116,314558,3726504,46310523, 599691087,8051875596,111674902936,1595269110991, 23416737953975,352551682694096,5435771974479840, 85722307390977058,1381216396128765272, 22718307467700650259,381156536404199989205] |