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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 5 |
| 7 | 13 |
| 8 | 31 |
| 9 | 121 |
| 10 | 491 |
| 11 | 3363 |
| 12 | 25731 |
| 13 | 206631 |
| 14 | 2160127 |
| 15 | 27517339 |
| 16 | 451415709 |
| 17 | 9252755391 |
| 18 | 223401136265 |
| 19 | 6569403284147 |
| 20 | 238066497574789 |
| 21 | 10727503069730095 |
| 22 | 599422231400326251 |
| 23 | 40846404956905305813 |
| 24 | 3394537590955437316889 |
[1,1,1,1,1,5,13,31,121,491,3363,25731,206631, 2160127,27517339,451415709,9252755391, 223401136265,6569403284147,238066497574789, 10727503069730095,599422231400326251, 40846404956905305813,3394537590955437316889] |