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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 3 |
| 6 | 7 |
| 7 | 19 |
| 8 | 43 |
| 9 | 167 |
| 10 | 933 |
| 11 | 5533 |
| 12 | 35651 |
| 13 | 275619 |
| 14 | 2803985 |
| 15 | 35280241 |
| 16 | 511587387 |
| 17 | 8841277573 |
| 18 | 187861018789 |
| 19 | 4919632132323 |
| 20 | 154644209783001 |
[1,1,1,1,3,7,19,43,167,933,5533,35651,275619, 2803985,35280241,511587387,8841277573, 187861018789,4919632132323,154644209783001] |