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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 20 |
| 3 | 81 |
| 4 | 292 |
| 5 | 1273 |
| 6 | 4616 |
| 7 | 17657 |
| 8 | 68780 |
| 9 | 277580 |
| 10 | 1109524 |
| 11 | 4407884 |
| 12 | 17603241 |
| 13 | 70401804 |
| 14 | 281550128 |
| 15 | 1126305456 |
[1,5,20,81,292,1273,4616,17657,68780,277580, 1109524,4407884,17603241,70401804,281550128, 1126305456] |