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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 6 |
| 6 | 39 |
| 7 | 209 |
| 8 | 947 |
| 9 | 4403 |
| 10 | 20825 |
| 11 | 95461 |
| 12 | 420312 |
| 13 | 1824610 |
| 14 | 7767715 |
| 15 | 32447127 |
| 16 | 133426790 |
| 17 | 540454735 |
| 18 | 2157136063 |
| 19 | 8491433827 |
| 20 | 32994222337 |
| 21 | 126618582468 |
| 22 | 480170037501 |
| 23 | 1800457116471 |
| 24 | 6678324836291 |
| 25 | 24515228772443 |
| 26 | 89097534819082 |
[1,1,2,3,6,39,209,947,4403,20825,95461,420312, 1824610,7767715,32447127,133426790,540454735, 2157136063,8491433827,32994222337,126618582468, 480170037501,1800457116471,6678324836291, 24515228772443,89097534819082] |