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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 12 |
| 6 | 30 |
| 7 | 80 |
| 8 | 221 |
| 9 | 624 |
| 10 | 1798 |
| 11 | 5271 |
| 12 | 15662 |
| 13 | 47052 |
| 14 | 142686 |
| 15 | 436187 |
| 16 | 1342669 |
| 17 | 4158048 |
| 18 | 12945758 |
| 19 | 40497415 |
| 20 | 127225426 |
| 21 | 401222453 |
| 22 | 1269712425 |
| 23 | 4030877287 |
| 24 | 12833659158 |
| 25 | 40968993548 |
| 26 | 131106215470 |
| 27 | 420507819784 |
| 28 | 1351562339222 |
| 29 | 4352564765053 |
| 30 | 14042486582525 |
[1,1,1,2,5,12,30,80,221,624,1798,5271,15662,47052, 142686,436187,1342669,4158048,12945758,40497415, 127225426,401222453,1269712425,4030877287, 12833659158,40968993548,131106215470,420507819784, 1351562339222,4352564765053,14042486582525] |