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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 7 |
| 4 | 81 |
| 5 | 1311 |
| 6 | 27273 |
| 7 | 693351 |
| 8 | 20830113 |
| 9 | 722035503 |
| 10 | 28364200569 |
| 11 | 1245313236663 |
| 12 | 60429110073489 |
| 13 | 3211572892464639 |
| 14 | 185523138537151977 |
| 15 | 11574425593731913479 |
| 16 | 775591270444009771137 |
| 17 | 55555665263291738684367 |
| 18 | 4236182199641241492147801 |