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 | 16 |
| 4 | 65 |
| 5 | 251 |
| 6 | 1016 |
| 7 | 4117 |
| 8 | 16913 |
| 9 | 69865 |
| 10 | 290455 |
| 11 | 1212905 |
| 12 | 5085224 |
| 13 | 21389824 |
| 14 | 90226449 |
| 15 | 381519416 |
| 16 | 1616684241 |
| 17 | 6863544233 |
| 18 | 29187402749 |
| 19 | 124305180842 |
| 20 | 530108333515 |
| 21 | 2263423401745 |
| 22 | 9674857844129 |
| 23 | 41396075156859 |
| 24 | 177285394355336 |
| 25 | 759895396193376 |
| 26 | 3259667597627576 |
| 27 | 13992851410449865 |