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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 16 |
| 3 | 106 |
| 4 | 578 |
| 5 | 2954 |
| 6 | 15064 |
| 7 | 75908 |
| 8 | 380334 |
| 9 | 1904330 |
| 10 | 9528618 |
| 11 | 47654840 |
| 12 | 238295096 |
| 13 | 1191556256 |
| 14 | 5957936770 |
| 15 | 29789860126 |
| 16 | 148950201902 |
| 17 | 744752899780 |
| 18 | 3723767329212 |
| 19 | 18618843605284 |
| 20 | 93094240114350 |
| 21 | 465471240742354 |
| 22 | 2327356261817746 |
| 23 | 11636781564585616 |
[0,2,16,106,578,2954,15064,75908,380334,1904330, 9528618,47654840,238295096,1191556256,5957936770, 29789860126,148950201902,744752899780, 3723767329212,18618843605284,93094240114350, 465471240742354,2327356261817746, 11636781564585616] |