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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 16 |
| 5 | 75 |
| 6 | 560 |
| 7 | 7772 |
| 8 | 202546 |
| 9 | 9955274 |
| 10 | 911146844 |
| 11 | 154541913254 |
| 12 | 48588413940171 |
| 13 | 28410569347709449 |
| 14 | 31024350279787141361 |
| 15 | 63532688288261802284578 |
| 16 | 244915643061880269492533777 |
| 17 | 1783405573307429828266152750816 |
| 18 | 24605670701967180148649252153837623 |
[1,1,2,5,16,75,560,7772,202546,9955274,911146844, 154541913254,48588413940171,28410569347709449, 31024350279787141361,63532688288261802284578, 244915643061880269492533777, 1783405573307429828266152750816, 24605670701967180148649252153837623] |