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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 3 |
| 4 | 6 |
| 5 | 110 |
| 6 | 1095 |
| 7 | 7161 |
| 8 | 37919 |
| 9 | 182367 |
| 10 | 860400 |
| 11 | 3893395 |
| 12 | 17126571 |
| 13 | 73368945 |
| 14 | 300879670 |
| 15 | 1173812745 |
| 16 | 4380376770 |
| 17 | 15753693858 |
| 18 | 54909242667 |
| 19 | 186135465987 |
| 20 | 614751720490 |
| 21 | 1979351435670 |
| 22 | 6214975736739 |
| 23 | 19042979887371 |
| 24 | 57000797449509 |
[1,3,6,110,1095,7161,37919,182367,860400,3893395, 17126571,73368945,300879670,1173812745,4380376770, 15753693858,54909242667,186135465987,614751720490, 1979351435670,6214975736739,19042979887371, 57000797449509] |