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 | 1 |
| 2 | 5 |
| 3 | 27 |
| 4 | 195 |
| 5 | 1833 |
| 6 | 21125 |
| 7 | 286451 |
| 8 | 4453859 |
| 9 | 78031153 |
| 10 | 1520668645 |
| 11 | 32631020011 |
| 12 | 764640901539 |
| 13 | 19431070911513 |
| 14 | 532315915981605 |
| 15 | 15640217893829891 |
| 16 | 490640673319698179 |
| 17 | 16368499360721508833 |
| 18 | 578693283962999831365 |