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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 31 |
| 5 | 157 |
| 6 | 864 |
| 7 | 5024 |
| 8 | 30370 |
| 9 | 188941 |
| 10 | 1201771 |
| 11 | 7779443 |
| 12 | 51083531 |
| 13 | 339437226 |
| 14 | 2278112737 |
| 15 | 15420424861 |
| 16 | 105152580575 |
| 17 | 721670737533 |
| 18 | 4981038781815 |
| 19 | 34552941731249 |
| 20 | 240769486524417 |
| 21 | 1684502378190617 |
| 22 | 11828416221973412 |
| 23 | 83333705758153522 |
| 24 | 588880900214492672 |
[0,1,2,7,31,157,864,5024,30370,188941,1201771, 7779443,51083531,339437226,2278112737,15420424861, 105152580575,721670737533,4981038781815, 34552941731249,240769486524417,1684502378190617, 11828416221973412,83333705758153522, 588880900214492672] |