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 | 2 |
| 3 | 11 |
| 4 | 74 |
| 5 | 635 |
| 6 | 6296 |
| 7 | 70268 |
| 8 | 864106 |
| 9 | 11546531 |
| 10 | 165996792 |
| 11 | 2548556963 |
| 12 | 41546769324 |
| 13 | 715850868468 |
| 14 | 12986529841038 |
| 15 | 247255748839532 |
| 16 | 4926870211273246 |
| 17 | 102495266879754087 |
| 18 | 2221254395951869988 |
| 19 | 50049980203162990978 |
| 20 | 1170440788530570387644 |