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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 19 |
| 6 | 71 |
| 7 | 274 |
| 8 | 1117 |
| 9 | 4650 |
| 10 | 19819 |
| 11 | 85710 |
| 12 | 375712 |
| 13 | 1664203 |
| 14 | 7439593 |
| 15 | 33515758 |
| 16 | 152019560 |
| 17 | 693625265 |
| 18 | 3181528275 |
| 19 | 14661581030 |
| 20 | 67850297506 |
| 21 | 315187646601 |
| 22 | 1469195636293 |
| 23 | 6869889703638 |
| 24 | 32215399021901 |
| 25 | 151467334017864 |
| 26 | 713881817440421 |
| 27 | 3372142139764434 |
[1,1,2,6,19,71,274,1117,4650,19819,85710,375712, 1664203,7439593,33515758,152019560,693625265, 3181528275,14661581030,67850297506,315187646601, 1469195636293,6869889703638,32215399021901, 151467334017864,713881817440421,3372142139764434] |