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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 5 |
| 7 | 15 |
| 8 | 35 |
| 9 | 70 |
| 10 | 140 |
| 11 | 252 |
| 12 | 420 |
| 13 | 660 |
| 14 | 990 |
| 15 | 1485 |
| 16 | 2145 |
| 17 | 3003 |
| 18 | 4095 |
| 19 | 5460 |
| 20 | 7280 |
| 21 | 9520 |
| 22 | 12240 |
| 23 | 15504 |
| 24 | 19381 |
| 25 | 24226 |
| 26 | 29926 |
| 27 | 36576 |
| 28 | 44276 |
| 29 | 53135 |
| 30 | 63761 |
| 31 | 75905 |
| 32 | 89705 |
| 33 | 105305 |
| 34 | 122865 |
| 35 | 143340 |
| 36 | 166272 |
| 37 | 191850 |
| 38 | 220270 |
| 39 | 251755 |
| 40 | 287715 |
| 41 | 327395 |
| 42 | 371043 |
[0,0,0,0,1,5,15,35,70,140,252,420,660,990,1485, 2145,3003,4095,5460,7280,9520,12240,15504,19381, 24226,29926,36576,44276,53135,63761,75905,89705, 105305,122865,143340,166272,191850,220270,251755, 287715,327395,371043] |