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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 41 |
| 4 | 285 |
| 5 | 2081 |
| 6 | 14965 |
| 7 | 108121 |
| 8 | 780045 |
| 9 | 5630161 |
| 10 | 40631525 |
| 11 | 293240201 |
| 12 | 2116305405 |
| 13 | 15273370241 |
| 14 | 110227737685 |
| 15 | 795512612281 |
| 16 | 5741206864365 |
| 17 | 41434236118321 |
| 18 | 299030490421445 |
| 19 | 2158100230000361 |
| 20 | 15574988996744925 |
| 21 | 112404548663730401 |
| 22 | 811222567266570805 |
[0,1,5,41,285,2081,14965,108121,780045,5630161, 40631525,293240201,2116305405,15273370241, 110227737685,795512612281,5741206864365, 41434236118321,299030490421445,2158100230000361, 15574988996744925,112404548663730401, 811222567266570805] |