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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 54 |
| 5 | 519 |
| 6 | 6397 |
| 7 | 96172 |
| 8 | 1706424 |
| 9 | 34904925 |
| 10 | 808662337 |
| 11 | 20928958434 |
| 12 | 598464096008 |
| 13 | 18737698303219 |
| 14 | 637544979358213 |
| 15 | 23423517214147512 |
| 16 | 924197264434029488 |
| 17 | 38975247881426173689 |
| 18 | 1749531623930002416225 |
| 19 | 83286004855369026615166 |
| 20 | 4191066886993961276317856 |
[1,1,2,8,54,519,6397,96172,1706424,34904925, 808662337,20928958434,598464096008,18737698303219, 637544979358213,23423517214147512, 924197264434029488,38975247881426173689, 1749531623930002416225,83286004855369026615166, 4191066886993961276317856] |