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) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 18 |
| 4 | 89 |
| 5 | 466 |
| 6 | 2537 |
| 7 | 14209 |
| 8 | 81316 |
| 9 | 473338 |
| 10 | 2793454 |
| 11 | 16674417 |
| 12 | 100487896 |
| 13 | 610549829 |
| 14 | 3735850007 |
| 15 | 23000055178 |
| 16 | 142370597601 |
| 17 | 885521350882 |
| 18 | 5531501612071 |
| 19 | 34686798239678 |
| 20 | 218273864005214 |
| 21 | 1377897874711437 |