This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 44 |
| 5 | 350 |
| 6 | 4292 |
| 7 | 57036 |
| 8 | 996088 |
| 9 | 18661152 |
| 10 | 424241102 |
| 11 | 10266964015 |
| 12 | 287927722315 |
| 13 | 8541887839459 |
| 14 | 285144784116376 |
| 15 | 10016752944160536 |
| 16 | 388044155110294856 |
| 17 | 15749295719801313452 |
| 18 | 694726457246902921502 |