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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 15 |
| 5 | 35 |
| 6 | 315 |
| 7 | 693 |
| 8 | 9009 |
| 9 | 19305 |
| 10 | 328185 |
| 11 | 692835 |
| 12 | 14549535 |
| 13 | 30421755 |
| 14 | 760543875 |
| 15 | 1579591125 |
| 16 | 45808142625 |
| 17 | 94670161425 |
| 18 | 3124115327025 |
| 19 | 6432002143875 |
| 20 | 237984079323375 |
| 21 | 488493636505875 |
| 22 | 20028239096740875 |
[1,1,3,15,35,315,693,9009,19305,328185,692835, 14549535,30421755,760543875,1579591125, 45808142625,94670161425,3124115327025, 6432002143875,237984079323375,488493636505875, 20028239096740875] |