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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 115 |
| 6 | 628 |
| 7 | 3818 |
| 8 | 25455 |
| 9 | 183968 |
| 10 | 1428184 |
| 11 | 11824098 |
| 12 | 103794727 |
| 13 | 961461179 |
| 14 | 9360372700 |
| 15 | 95448502365 |
| 16 | 1016413911387 |
| 17 | 11273822075837 |
| 18 | 129950445723958 |
| 19 | 1553488011957986 |
| 20 | 19225242250821071 |
| 21 | 245899882175001580 |
| 22 | 3245812116097119188 |
| 23 | 44155099624566615247 |
[0,1,2,6,24,115,628,3818,25455,183968,1428184, 11824098,103794727,961461179,9360372700, 95448502365,1016413911387,11273822075837, 129950445723958,1553488011957986, 19225242250821071,245899882175001580, 3245812116097119188,44155099624566615247] |