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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 19 |
| 4 | 70 |
| 5 | 262 |
| 6 | 1031 |
| 7 | 4153 |
| 8 | 17104 |
| 9 | 71585 |
| 10 | 303758 |
| 11 | 1303324 |
| 12 | 5645184 |
| 13 | 24647181 |
| 14 | 108364268 |
| 15 | 479285899 |
| 16 | 2131180012 |
| 17 | 9520717770 |
| 18 | 42710777994 |
| 19 | 192323297051 |
| 20 | 868946783064 |
| 21 | 3938096694053 |
| 22 | 17897424213394 |
| 23 | 81546179597241 |
| 24 | 372420902761982 |
| 25 | 1704519540738366 |
| 26 | 7816936108095650 |
| 27 | 35914879901405947 |
[1,2,6,19,70,262,1031,4153,17104,71585,303758, 1303324,5645184,24647181,108364268,479285899, 2131180012,9520717770,42710777994,192323297051, 868946783064,3938096694053,17897424213394, 81546179597241,372420902761982,1704519540738366, 7816936108095650,35914879901405947] |