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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 2 |
| 5 | 5 |
| 6 | 13 |
| 7 | 31 |
| 8 | 80 |
| 9 | 201 |
| 10 | 533 |
| 11 | 1401 |
| 12 | 3822 |
| 13 | 10395 |
| 14 | 28859 |
| 15 | 80201 |
| 16 | 225286 |
| 17 | 634265 |
| 18 | 1796433 |
| 19 | 5100325 |
| 20 | 14534758 |
| 21 | 41513402 |
| 22 | 118879249 |
| 23 | 341094843 |
| 24 | 980661980 |
| 25 | 2824223490 |
| 26 | 8146897815 |
| 27 | 23535345170 |
[0,0,1,2,5,13,31,80,201,533,1401,3822,10395,28859, 80201,225286,634265,1796433,5100325,14534758, 41513402,118879249,341094843,980661980,2824223490, 8146897815,23535345170] |