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| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 1 |
| 6 | 4 |
| 7 | 9 |
| 8 | 28 |
| 9 | 71 |
| 10 | 202 |
| 11 | 542 |
| 12 | 1507 |
| 13 | 4114 |
| 14 | 11381 |
| 15 | 31349 |
| 16 | 86845 |
| 17 | 240567 |
| 18 | 668553 |
| 19 | 1860361 |
| 20 | 5188767 |
| 21 | 14495502 |
| 22 | 40572216 |
| 23 | 113743293 |
| 24 | 319405695 |
| 25 | 898288484 |
| 26 | 2530058013 |
| 27 | 7135848125 |
| 28 | 20152898513 |
| 29 | 56986883801 |
[1,1,4,9,28,71,202,542,1507,4114,11381,31349, 86845,240567,668553,1860361,5188767,14495502, 40572216,113743293,319405695,898288484,2530058013, 7135848125,20152898513,56986883801] |