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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 3 |
| 6 | 15 |
| 7 | 59 |
| 8 | 185 |
| 9 | 513 |
| 10 | 1429 |
| 11 | 4429 |
| 12 | 15157 |
| 13 | 53063 |
| 14 | 181075 |
| 15 | 601335 |
| 16 | 1986857 |
| 17 | 6668441 |
| 18 | 22844345 |
| 19 | 79190777 |
| 20 | 274979521 |
| 21 | 952675283 |
| 22 | 3299619927 |
| 23 | 11466715411 |
| 24 | 40054475169 |
| 25 | 140536413497 |
| 26 | 494404614557 |
| 27 | 1741798930389 |
| 28 | 6144137237061 |
[1,1,1,1,3,15,59,185,513,1429,4429,15157,53063, 181075,601335,1986857,6668441,22844345,79190777, 274979521,952675283,3299619927,11466715411, 40054475169,140536413497,494404614557, 1741798930389,6144137237061] |