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) |
|---|---|
| 1 | 0 |
| 2 | 5 |
| 3 | 45 |
| 4 | 351 |
| 5 | 2847 |
| 6 | 25047 |
| 7 | 241047 |
| 8 | 2534247 |
| 9 | 28984167 |
| 10 | 358842087 |
| 11 | 4785978087 |
| 12 | 68453274087 |
| 13 | 1045616538087 |
| 14 | 16993016806887 |
| 15 | 292825130163687 |
| 16 | 5333909818803687 |
| 17 | 102415654899123687 |
| 18 | 2067588695129523687 |
| 19 | 43785455761653171687 |
| 20 | 970599475776544179687 |