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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 14 |
| 5 | 40 |
| 6 | 121 |
| 7 | 373 |
| 8 | 1181 |
| 9 | 3796 |
| 10 | 12391 |
| 11 | 40902 |
| 12 | 136408 |
| 13 | 458735 |
| 14 | 1554220 |
| 15 | 5299505 |
| 16 | 18172874 |
| 17 | 62630809 |
| 18 | 216821747 |
| 19 | 753646690 |
| 20 | 2629153881 |
| 21 | 9202404515 |
| 22 | 32307100270 |
| 23 | 113735363082 |
| 24 | 401418269205 |
| 25 | 1420094167064 |
| 26 | 5034768842706 |
| 27 | 17886133630919 |
| 28 | 63660082770995 |
[1,1,2,5,14,40,121,373,1181,3796,12391,40902, 136408,458735,1554220,5299505,18172874,62630809, 216821747,753646690,2629153881,9202404515, 32307100270,113735363082,401418269205, 1420094167064,5034768842706,17886133630919, 63660082770995] |