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 | 3 |
| 2 | 15 |
| 3 | 197 |
| 4 | 6909 |
| 5 | 459383 |
| 6 | 48252699 |
| 7 | 7299708105 |
| 8 | 1499523879481 |
| 9 | 401147660278507 |
| 10 | 135421121289695655 |
| 11 | 56285769483090611085 |
| 12 | 28237152577765405343285 |
| 13 | 16821061018350834178553055 |