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) |
|---|---|
| 2 | 1 |
| 3 | 5 |
| 4 | 28 |
| 5 | 156 |
| 6 | 880 |
| 7 | 5005 |
| 8 | 28665 |
| 9 | 165104 |
| 10 | 955434 |
| 11 | 5550755 |
| 12 | 32355917 |
| 13 | 189147400 |
| 14 | 1108476720 |
| 15 | 6510243495 |
| 16 | 38308997100 |
| 17 | 225810489168 |
| 18 | 1333057076890 |