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 | 0 |
| 2 | 3 |
| 3 | 18 |
| 4 | 138 |
| 5 | 1278 |
| 6 | 13410 |
| 7 | 154584 |
| 8 | 1919352 |
| 9 | 25273422 |
| 10 | 348989058 |
| 11 | 5011939788 |
| 12 | 74393974476 |
| 13 | 1135821378924 |