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 | 1 |
| 2 | 4 |
| 3 | 33 |
| 4 | 309 |
| 5 | 2805 |
| 6 | 25566 |
| 7 | 230989 |
| 8 | 2106529 |
| 9 | 19303539 |
| 10 | 177948527 |
| 11 | 1649241049 |
| 12 | 15360074924 |
| 13 | 143682925080 |