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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 28 |
| 2 | 210 |
| 3 | 924 |
| 4 | 3003 |
| 5 | 8008 |
| 6 | 18564 |
| 7 | 38760 |
| 8 | 74613 |
| 9 | 134596 |
| 10 | 230230 |
| 11 | 376740 |
| 12 | 593775 |
| 13 | 906192 |
| 14 | 1344904 |
| 15 | 1947792 |
| 16 | 2760681 |
| 17 | 3838380 |
| 18 | 5245786 |
| 19 | 7059052 |
| 20 | 9366819 |
| 21 | 12271512 |
| 22 | 15890700 |
| 23 | 20358520 |
| 24 | 25827165 |
| 25 | 32468436 |
| 26 | 40475358 |
| 27 | 50063860 |
| 28 | 61474519 |
| 29 | 74974368 |
| 30 | 90858768 |
[1,28,210,924,3003,8008,18564,38760,74613,134596, 230230,376740,593775,906192,1344904,1947792, 2760681,3838380,5245786,7059052,9366819,12271512, 15890700,20358520,25827165,32468436,40475358, 50063860,61474519,74974368,90858768] |