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 | 1 |
| 2 | 5 |
| 3 | 34 |
| 4 | 303 |
| 5 | 3371 |
| 6 | 45016 |
| 7 | 701401 |
| 8 | 12490057 |
| 9 | 250215916 |
| 10 | 5569582777 |
| 11 | 136371309999 |
| 12 | 3642603629462 |
| 13 | 105405416033607 |
| 14 | 3284722016179597 |
| 15 | 109672448519030698 |
| 16 | 3905936524326557659 |
| 17 | 147802493781420536423 |
| 18 | 5921911678533323178312 |