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| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 6 |
| 2 | 19 |
| 3 | 34 |
| 4 | 100 |
| 5 | 241 |
| 6 | 697 |
| 7 | 1779 |
| 8 | 6590 |
| 9 | 16585 |
| 10 | 57237 |
| 11 | 179291 |
| 12 | 591325 |
| 13 | 1707010 |
| 14 | 6520756 |
| 15 | 18271423 |
| 16 | 65212230 |
| 17 | 210339179 |
| 18 | 706823539 |
[4,6,19,34,100,241,697,1779,6590,16585,57237, 179291,591325,1707010,6520756,18271423,65212230, 210339179,706823539] |