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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 42 |
| 3 | 308 |
| 4 | 734 |
| 5 | 4906 |
| 6 | 13170 |
| 7 | 82526 |
| 8 | 239992 |
| 9 | 1398710 |
| 10 | 4333362 |
| 11 | 23808020 |
| 12 | 77703762 |
| 13 | 406751730 |
| 14 | 1385692672 |
| 15 | 6971295054 |
| 16 | 24603895150 |
| 17 | 119805137680 |
| 18 | 435349233940 |
| 19 | 2063663956954 |
| 20 | 7681867046626 |
| 21 | 35616414149972 |
| 22 | 135245995065394 |
[1,42,308,734,4906,13170,82526,239992,1398710, 4333362,23808020,77703762,406751730,1385692672, 6971295054,24603895150,119805137680,435349233940, 2063663956954,7681867046626,35616414149972, 135245995065394] |