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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 19 |
| 5 | 65 |
| 6 | 211 |
| 7 | 681 |
| 8 | 2255 |
| 9 | 7830 |
| 10 | 28786 |
| 11 | 111230 |
| 12 | 443789 |
| 13 | 1795972 |
| 14 | 7284981 |
| 15 | 29466755 |
| 16 | 118834438 |
| 17 | 479034654 |
| 18 | 1936617163 |
| 19 | 7872885832 |
| 20 | 32226147305 |
| 21 | 132808096158 |
| 22 | 550444192577 |
| 23 | 2291095125465 |
| 24 | 9564074472264 |
| 25 | 40005894288101 |
| 26 | 167610376198140 |
| 27 | 703308153554903 |
[1,0,1,5,19,65,211,681,2255,7830,28786,111230, 443789,1795972,7284981,29466755,118834438, 479034654,1936617163,7872885832,32226147305, 132808096158,550444192577,2291095125465, 9564074472264,40005894288101,167610376198140, 703308153554903] |