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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 14 |
| 5 | 42 |
| 6 | 131 |
| 7 | 421 |
| 8 | 1386 |
| 9 | 4654 |
| 10 | 15886 |
| 11 | 54978 |
| 12 | 192509 |
| 13 | 680899 |
| 14 | 2429418 |
| 15 | 8734395 |
| 16 | 31613985 |
| 17 | 115109388 |
| 18 | 421354939 |
| 19 | 1549721348 |
| 20 | 5724315670 |
| 21 | 21226681986 |
| 22 | 78990800097 |
| 23 | 294899059900 |
| 24 | 1104220030505 |
| 25 | 4145909987441 |
| 26 | 15605386349552 |
| 27 | 58875964968523 |
[1,1,2,5,14,42,131,421,1386,4654,15886,54978, 192509,680899,2429418,8734395,31613985,115109388, 421354939,1549721348,5724315670,21226681986, 78990800097,294899059900,1104220030505, 4145909987441,15605386349552,58875964968523] |