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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 25 |
| 4 | 135 |
| 5 | 775 |
| 6 | 4651 |
| 7 | 28845 |
| 8 | 183450 |
| 9 | 1190050 |
| 10 | 7844230 |
| 11 | 52389678 |
| 12 | 353770190 |
| 13 | 2411324700 |
| 14 | 16568343325 |
| 15 | 114639216915 |
| 16 | 798076174113 |
| 17 | 5586035989185 |
| 18 | 39287407321075 |
| 19 | 277508001643575 |
| 20 | 1967816928168265 |
| 21 | 14003018984540741 |
| 22 | 99965175670335750 |
[1,1,5,25,135,775,4651,28845,183450,1190050, 7844230,52389678,353770190,2411324700,16568343325, 114639216915,798076174113,5586035989185, 39287407321075,277508001643575,1967816928168265, 14003018984540741,99965175670335750] |